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Light isovector resonances in $\pi^- p \to \pi^-\pi^-\pi^+ p$ at 190 GeV/${\it c}$
M. Aghasyan, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, et al (205)
Feb 19 2018 hep-ex hep-ph arXiv:1802.05913v2

@misc{1802.05913, author = {M.~Aghasyan and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and A.~Antoshkin and K.~Augsten and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and M.~Ball and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and M.~Bodlak and P.~Bordalo and F.~Bradamante and A.~Bressan and M.~Buechele and V.E.~Burtsev and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and A.G.~Chumakov and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and Ch.~Dreisbach and W.~Duennweber and R.R.~Dusaev and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and J.~Giarra and I.~Gnesi and M.~Gorzellik and A.~Grasso and A.~Gridin and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Hass and D.~Hahne and G.~Hamar and D.~von Harrach and R.~Heitz and F.~Herrmann and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and V.~Jary and R.~Joosten and P.~Joerg and K.~Juraskova and E.~Kabuss and A.~Kerbizi and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and Z.~Kral and M.~Kraemer and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and I.I.~Kuznetsov and A.~Kveton and A.A.~Lednev and E.A.~Levchenko and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and V.E.~Lyubovitskij and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and S.A.~Mamon and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and A.~Moretti and A.~Nagaytsev and F.~Nerling and D.~Neyret and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and M.~Peskova and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and N.~S.~Rogacheva and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and T.~Schluter and S.~Schmeing and H.~Schmieden and E.~Seder and A.~Selyunin and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and A.~Srnka and D.~Steffen and M.~Stolarski and O.~Subrt and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and A.~Thiel and J.~Tomsa and F.~Tosello and V.~Tskhay and S.~Uhl and B.I.~Vasilishin and A.~Vauth and B.M.~Veit and J.~Veloso and A.Vidon and M.~Virius and S.~Wallner and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki}, title = {{L}ight isovector resonances in $\pi^- p \to \pi^-\pi^-\pi^+ p$ at 190 {G}e{V}/${\it c}$}, year = {2018}, eprint = {1802.05913}, note = {arXiv:1802.05913v2} }
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We have performed the most comprehensive resonance-model fit of $\pi^-\pi^-\pi^+$ states using the results of our previously published partial-wave analysis (PWA) of a large data set of diffractive-dissociation events from the reaction $\pi^- + p \to \pi^-\pi^-\pi^+ + p_\text{recoil}$ with a 190 GeV/$c$ pion beam. The PWA results, which were obtained in 100 bins of three-pion mass, $0.5 < m_{3\pi} < 2.5$ GeV/$c^2$, and simultaneously in 11 bins of the reduced four-momentum transfer squared, $0.1 < t' < 1.0$ $($GeV$/c)^2$, are subjected to a resonance-model fit using Breit-Wigner amplitudes to simultaneously describe a subset of 14 selected waves using 11 isovector light-meson states with $J^{PC} = 0^{-+}$, $1^{++}$, $2^{++}$, $2^{-+}$, $4^{++}$, and spin-exotic $1^{-+}$ quantum numbers. The model contains the well-known resonances $\pi(1800)$, $a_1(1260)$, $a_2(1320)$, $\pi_2(1670)$, $\pi_2(1880)$, and $a_4(2040)$. In addition, it includes the disputed $\pi_1(1600)$, the excited states $a_1(1640)$, $a_2(1700)$, and $\pi_2(2005)$, as well as the resonancelike $a_1(1420)$. We measure the resonance parameters mass and width of these objects by combining the information from the PWA results obtained in the 11 $t'$ bins. We extract the relative branching fractions of the $\rho(770) \pi$ and $f_2(1270) \pi$ decays of $a_2(1320)$ and $a_4(2040)$, where the former one is measured for the first time. In a novel approach, we extract the $t'$ dependence of the intensity of the resonances and of their phases. The $t'$ dependence of the intensities of most resonances differs distinctly from the $t'$ dependence of the nonresonant components. For the first time, we determine the $t'$ dependence of the phases of the production amplitudes and confirm that the production mechanism of the Pomeron exchange is common to all resonances.
Transverse Extension of Partons in the Proton probed by Deeply Virtual Compton Scattering
R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, et al (207)
Feb 09 2018 hep-ex nucl-ex arXiv:1802.02739v2

@misc{1802.02739, author = {R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and A.~Antoshkin and K.~Augsten and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and M.~Ball and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and M.~Bodlak and P.~Bordalo and F.~Bradamante and A.~Bressan and M.~Buechele and E.~Burtin and V.E.~Burtsev and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and A.G.~Chumakov and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and Ch.~Dreisbach and W.~Duennweber and R.R.~Dusaev and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and J.~Giarra and I.~Gnesi and M.~Gorzellik and A.~Grasso and A.~Gridin and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and D.~Hahne and G.~Hamar and D.~von Harrach and R.~Heitz and F.~Herrmann and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and V.~Jary and R.~Joosten and P.~Joerg and K.~Juraskova and E.~Kabuss and A.~Kerbizi and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and Z.~Kral and M.~Kraemer and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and I.I.~Kuznetsov and A.~Kveton and A.A.~Lednev and E.A.~Levchenko and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and V.E.~Lyubovitskij and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and S.A.~Mamon and C.~Marchand and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and A.~Moretti and A.~Nagaytsev and F.~Nerling and D.~Neyret and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and G.~Pesaro and M.~Pesek and M.~Peskova and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and N.~S.~Rogacheva and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and H.~Schmieden and K.~Schoennig and E.~Seder and A.~Selyunin and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and A.~Srnka and D.~Steffen and M.~Stolarski and O.~Subrt and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and A.~Thiel and J.~Tomsa and F.~Tosello and V.~Tskhay and S.~Uhl and B.I.~Vasilishin and A.~Vauth and B.~M.~Veit and J.~Veloso and A.Vidon and M.~Virius and S.~Wallner and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and N.~Zhuravlev and M.~Ziembicki}, title = {{T}ransverse {E}xtension of {P}artons in the {P}roton probed by {D}eeply {V}irtual {C}ompton {S}cattering}, year = {2018}, eprint = {1802.02739}, doi = {10.1016/j.physletb.2019.04.038}, note = {arXiv:1802.02739v2} }
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We report on the first measurement of exclusive single-photon muoproduction on the proton by COMPASS using 160 GeV/$c$ polarized $\mu^+$ and $\mu^-$ beams of the CERN SPS impinging on a liquid hydrogen target. We determine the dependence of the average of the measured $\mu^+$ and $\mu^-$ cross sections for deeply virtual Compton scattering on the squared four-momentum transfer $t$ from the initial to the final final proton. The slope $B$ of the $t$-dependence is fitted with a single exponential function, which yields $B=(4.3 \ \pm \ 0.6_{\text{stat}}\_{- \ 0.3}^{+ \ 0.1}\big\rvert_{\text{sys}}) (\text{GeV}/c)^{-2}$. This result can be converted into an average transverse extension of partons in the proton, $\sqrt{\langle r_{\perp}^2 \rangle} = (0.58 \ \pm \ 0.04_{\text{stat}}\_{- \ 0.02}^{+ \ 0.01}\big\rvert_{\text{sys}})\text{fm}$. For this measurement, the average virtuality of the photon mediating the interaction is $\langle Q^2 \rangle = 1.8\,(\text{GeV/}c)^2$ and the average value of the Bjorken variable is $\langle x_{\text{Bj}} \rangle = 0.056$.
Longitudinal double-spin asymmetry $A_1^{\rm p}$ and spin-dependent structure function $g_1^{\rm p}$ of the proton at small values of $x$ and $Q^2$
M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, et al (209)
Oct 04 2017 hep-ex arXiv:1710.01014v1

@misc{1710.01014, author = {M.~Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and A.~Antoshkin and K.~Augsten and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and M.~Ball and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and M.~Bodlak and P.~Bordalo and F.~Bradamante and A.~Bressan and M.~Buechele and V.E.~Burtsev and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and A.G.~Chumakov and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and Ch.~Dreisbach and W.~Duennweber and R.R.~Dusaev and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and J.~Giarra and F.~Giordano and I.~Gnesi and M.~Gorzellik and A.~Grasso and A.~Gridin and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and D.~Hahne and G.~Hamar and D.~von Harrach and F.H.~Heinsius and R.~Heitz and F.~Herrmann and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and V.~Jary and R.~Joosten and P.~Joerg and E.~Kabuss and A.~Kerbizi and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and Z.~Kral and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and I.I.~Kuznetsov and A.~Kveton and A.A.~Lednev and E.A.~Levchenko and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and V.E.~Lyubovitskij and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and S.A.~Mamon and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and A.~Moretti and A.~Nagaytsev and F.~Nerling and D.~Neyret and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and M.~Peskova and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and N.S.~Rogacheva and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and E.~Seder and A.~Selyunin and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and A.~Srnka and D.~Steffen and M.~Stolarski and O.~Subrt and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and A.~Thiel and J.~Tomsa and F.~Tosello and V.~Tskhay and S.~Uhl and B.I.~Vasilishin and A.~Vauth and J.~Veloso and A.Vidon and M.~Virius and S.~Wallner and T.~Weisrock and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and N.~Zhuravlev and M.~Ziembicki}, title = {{L}ongitudinal double-spin asymmetry ${A}_1^{\rm p}$ and spin-dependent structure function $g_1^{\rm p}$ of the proton at small values of $x$ and ${Q}^2$}, year = {2017}, eprint = {1710.01014}, note = {arXiv:1710.01014v1} }
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We present a precise measurement of the proton longitudinal double-spin asymmetry $A_1^{\rm p}$ and the proton spin-dependent structure function $g_1^{\rm p}$ at photon virtualities $0.006~({\rm GeV}/c)^2<Q^2 < 1~({\rm GeV}/c)^2$ in the Bjorken $x$ range of $4 \times 10^{-5} < x < 4 \times 10^{-2}$. The results are based on data collected by the COMPASS Collaboration at CERN using muon beam energies of $160~{\rm GeV}$ and $200~{\rm GeV}$. The statistical precision is more than tenfold better than that of the previous measurement in this region. In the whole range of $x$, the measured values of $A_1^{\rm p}$ and $g_1^{\rm p}$ are found to be positive. It is for the first time that spin effects are found at such low values of $x$.
Transverse-momentum-dependent Multiplicities of Charged Hadrons in Muon-Deuteron Deep Inelastic Scattering
M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, et al (211)
Sep 22 2017 hep-ex nucl-ex arXiv:1709.07374v1

@misc{1709.07374, author = {M.~Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and A.~Antoshkin and K.~Augsten and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and M.~Ball and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and M.~Bodlak and P.~Bordalo and F.~Bradamante and A.~Bressan and M.~Buechele and V.E.~Burtsev and L.~Capozza and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and A.G.~Chumakov and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and Ch.~Dreisbach and W.~Duennweber and R.R.~Dusaev and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and J.~Giarra and F.~Giordano and I.~Gnesi and M.~Gorzellik and A.~Grasso and A.~Gridin and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and D.~Hahne and G.~Hamar and D.~von Harrach and F.H.~Heinsius and R.~Heitz and F.~Herrmann and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and V.~Jary and R.~Joosten and P.~Joerg and E.~Kabuss and A.~Kerbizi and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and Z.~Kral and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and I.I.~Kuznetsov and A.~Kveton and A.A.~Lednev and E.A.~Levchenko and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and V.E.~Lyubovitskij and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and S.A.~Mamon and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and A.~Moretti and A.~Nagaytsev and F.~Nerling and D.~Neyret and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and M.~Peskova and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and N.S.~Rogacheva and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and E.~Seder and A.~Selyunin and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and A.~Srnka and D.~Steffen and M.~Stolarski and O.~Subrt and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and A.~Thiel and J.~Tomsa and F.~Tosello and V.~Tskhay and S.~Uhl and B.I.~Vasilishin and A.~Vauth and J.~Veloso and A.Vidon and M.~Virius and S.~Wallner and T.~Weisrock and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and N.~Zhuravlev and M.~Ziembicki}, title = {{T}ransverse-momentum-dependent {M}ultiplicities of {C}harged {H}adrons in {M}uon-{D}euteron {D}eep {I}nelastic {S}cattering}, year = {2017}, eprint = {1709.07374}, note = {arXiv:1709.07374v1} }
PDF
A semi-inclusive measurement of charged hadron multiplicities in deep inelastic muon scattering off an isoscalar target was performed using data collected by the COMPASS Collaboration at CERN. The following kinematic domain is covered by the data: photon virtuality $Q^{2}>1$ (GeV/$c$)$^2$, invariant mass of the hadronic system $W > 5$ GeV/$c^2$, Bjorken scaling variable in the range $0.003 < x < 0.4$, fraction of the virtual photon energy carried by the hadron in the range $0.2 < z < 0.8$, square of the hadron transverse momentum with respect to the virtual photon direction in the range 0.02 (GeV/$c)^2 < P_{\rm{hT}}^{2} < 3$ (GeV/$c$)$^2$. The multiplicities are presented as a function of $P_{\rm{hT}}^{2}$ in three-dimensional bins of $x$, $Q^2$, $z$ and compared to previous semi-inclusive measurements. We explore the small-$P_{\rm{hT}}^{2}$ region, i.e. $P_{\rm{hT}}^{2} < 1$ (GeV/$c$)$^2$, where hadron transverse momenta are expected to arise from non-perturbative effects, and also the domain of larger $P_{\rm{hT}}^{2}$, where contributions from higher-order perturbative QCD are expected to dominate. The multiplicities are fitted using a single-exponential function at small $P_{\rm{hT}}^{2}$ to study the dependence of the average transverse momentum $\langle P_{\rm{hT}}^{2}\rangle$ on $x$, $Q^2$ and $z$. The power-law behaviour of the multiplicities at large $P_{\rm{hT}}^{2}$ is investigated using various functional forms. The fits describe the data reasonably well over the full measured range.
New analysis of $\eta\pi$ tensor resonances measured at the COMPASS experiment
A. Jackura, C. Fernandez-Ramirez, M. Mikhasenko, A. Pilloni, V. Mathieu, J. Nys, V. Pauk, A. P. Szczepaniak, G. Fox, M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, et al (217)
Jul 11 2017 hep-ph hep-ex arXiv:1707.02848v1

@misc{1707.02848, author = {A.~Jackura and C.~Fernandez-Ramirez and M.~Mikhasenko and A.~Pilloni and V.~Mathieu and J.~Nys and V.~Pauk and A.~P.~Szczepaniak and G.~Fox and M.~Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and A.~Antoshkin and K.~Augsten and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and M.~Ball and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and M.~Bodlak and P.~Bordalo and F.~Bradamante and A.~Bressan and M.~Buechele and V.E.~Burtsev and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and A.G.~Chumakov and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and Ch.~Dreisbach and W.~Duennweber and R.R.~Dusaev and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and J.~Giarra and F.~Giordano and I.~Gnesi and M.~Gorzellik and A.~Grasso and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and D.~Hahne and G.~Hamar and D.~von Harrach and F.H.~Heinsius and R.~Heitz and F.~Herrmann and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and V.~Jary and R.~Joosten and P.~Joerg and E.~Kabuss and A.~Kerbizi and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and Z.~Kral and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and I.I.~Kuznetsov and A.~Kveton and A.A.~Lednev and E.A.~Levchenko and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and V.E.~Lyubovitskij and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and S.A.~Mamon and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and A.~Nagaytsev and F.~Nerling and D.~Neyret and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and M.~Peskova and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and N.S.~Rogacheva and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and T.~Schluter and K.~Schmidt and H.~Schmieden and K.~Schoenning and E.~Seder and A.~Selyunin and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and A.~Srnka and D.~Steffen and M.~Stolarski and O.~Subrt and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and A.~Thiel and J.~Tomsa and F.~Tosello and V.~Tskhay and S.~Uhl and B.I.~Vasilishin and A.~Vauth and J.~Veloso and A.Vidon and M.~Virius and S.~Wallner and T.~Weisrock and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and N.~Zhuravlev and M.~Ziembicki}, title = {{N}ew analysis of $\eta\pi$ tensor resonances measured at the {COMPASS} experiment}, year = {2017}, eprint = {1707.02848}, note = {arXiv:1707.02848v1} }
PDF
We present a new amplitude analysis of the $\eta\pi$ $D$-wave in $\pi^- p\to \eta\pi^- p$ measured by COMPASS. Employing an analytical model based on the principles of the relativistic $S$-matrix, we find two resonances that can be identified with the $a_2(1320)$ and the excited $a_2^\prime(1700)$, and perform a comprehensive analysis of their pole positions. For the mass and width of the $a_2$ we find $M=(1307 \pm 1 \pm 6)$~MeV and $\Gamma=(112 \pm 1 \pm 8)$~MeV, and for the excited state $a_2^\prime$ we obtain $M=(1720 \pm 10 \pm 60)$~MeV and $\Gamma=(280\pm 10 \pm 70)$~MeV, respectively.
Search for muoproduction of $X(3872)$ at COMPASS and indication of a new state $\widetilde{X}(3872)$
M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, et al (208)
Jul 07 2017 hep-ex arXiv:1707.01796v2

@misc{1707.01796, author = {M.~Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and A.~Antoshkin and K.~Augsten and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and M.~Ball and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and M.~Bodlak and P.~Bordalo and F.~Bradamante and A.~Bressan and M.~Buechele and V.E.~Burtsev and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and A.G.~Chumakov and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and Ch.~Dreisbach and W.~Duennweber and R.R.~Dusaev and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and J.~Giarra and F.~Giordano and I.~Gnesi and M.~Gorzellik and A.~Grasso and A.~Gridin and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and D.~Hahne and G.~Hamar and D.~von Harrach and F.H.~Heinsius and R.~Heitz and F.~Herrmann and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and V.~Jary and R.~Joosten and P.~Joerg and E.~Kabuss and A.~Kerbizi and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and Z.~Kral and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and I.I.~Kuznetsov and A.~Kveton and A.A.~Lednev and E.A.~Levchenko and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and V.E.~Lyubovitskij and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and S.A.~Mamon and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and A.~Nagaytsev and F.~Nerling and D.~Neyret and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and M.~Peskova and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and N.S.~Rogacheva and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and E.~Seder and A.~Selyunin and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and A.~Srnka and D.~Steffen and M.~Stolarski and O.~Subrt and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and A.~Thiel and J.~Tomsa and F.~Tosello and V.~Tskhay and S.~Uhl and B.I.~Vasilishin and A.~Vauth and J.~Veloso and A.Vidon and M.~Virius and S.~Wallner and T.~Weisrock and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and N.~Zhuravlev and M.~Ziembicki}, title = {{S}earch for muoproduction of ${X}(3872)$ at {COMPASS} and indication of a new state $\widetilde{{X}}(3872)$}, year = {2017}, eprint = {1707.01796}, doi = {10.1016/j.physletb.2018.07.008}, note = {arXiv:1707.01796v2} }
PDF
We have searched for exclusive production of exotic charmonia in the reaction $\mu^+~N \rightarrow \mu^+ (J\!/\!\psi\pi^+\pi^-)\pi^{\pm}~N'$ using COMPASS data collected with incoming muons of 160 GeV/$c$ and 200 GeV/$c$ momentum. In the $J\!/\!\psi\pi^+\pi^-$ mass distribution we observe a signal with a statistical significance of 4.1 $\sigma$. Its mass and width are consistent with those of the $X(3872)$. The shape of the $\pi^+\pi^-$ mass distribution from the observed decay into $J\!/\!\psi\pi^+\pi^-$ shows disagreement with previous observations for $X(3872)$. The observed signal may be interpreted as a possible evidence of a new charmonium state. It could be associated with a neutral partner of $X(3872)$ with $C = -1$ predicted by a tetraquark model. The product of cross section and branching fraction of the decay of the observed state into $J\!/\!\psi\pi^+\pi^-$ is determined to be 71$\pm$28(stat)$\pm$39(syst) pb.
First measurement of transverse-spin-dependent azimuthal asymmetries in the Drell-Yan process
Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, et al (200)
Apr 04 2017 hep-ex hep-ph arXiv:1704.00488v1

@misc{1704.00488, author = {Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and A.~Antoshkin and K.~Augsten and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and M.~Ball and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and M.~Bodlak and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and Ch.~Dreisbach and W.~Duennweber and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and J.~Giarra and F.~Giordano and I.~Gnesi and M.~Gorzellik and A.~Grasso and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and D.~Hahne and G.~Hamar and D.~von Harrach and F.H.~Heinsius and R.~Heitz and F.~Herrmann and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and V.~Jary and R.~Joosten and P.~Joerg and E.~Kabuss and A.~Kerbizi and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and Z.~Kral and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.~Kveton and A.A.~Lednev and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and A.~Nagaytsev and F.~Nerling and D.~Neyret and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and N.S.~Rogacheva and M.~Roskot and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and E.~Seder and A.~Selyunin and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and A.~Srnka and D.~Steffen and M.~Stolarski and O.~Subrt and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and A.~Thiel and J.~Tomsa and F.~Tosello and V.~Tskhay and S.~Uhl and A.~Vauth and J.~Veloso and M.~Virius and J.~Vondra and S.~Wallner and T.~Weisrock and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and N.~Zhuravlev and M.~Ziembicki}, title = {{F}irst measurement of transverse-spin-dependent azimuthal asymmetries in the {D}rell-{Y}an process}, year = {2017}, eprint = {1704.00488}, note = {arXiv:1704.00488v1} }
PDF
The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190 GeV/$c$, $\pi^{-}$ beam and a transversely polarized ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3 GeV/$c^2$ and 8.5 GeV/$c^2$. The observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of Quantum Chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic scattering (SIDIS) data. We present two other asymmetries originating from the pion Boer-Mulders TMD PDFs convoluted with either the nucleon transversity or pretzelosity TMD PDFs. These DY results are obtained at a hard scale comparable to that of a recent COMPASS SIDIS measurement and hence allow unique tests of fundamental QCD universality predictions.
First measurement of the Sivers asymmetry for gluons from SIDIS data
C. Adolph, M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, et al (207)
Jan 11 2017 hep-ex hep-ph arXiv:1701.02453v1

@misc{1701.02453, author = {C.~Adolph and M.~Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and A.~Antoshkin and K.~Augsten and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and M.~Ball and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and M.~Bodlak and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and Ch.~Dreisbach and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and J.~Giarra and F.~Giordano and I.~Gnesi and M.~Gorzellik and S.~Grabmueller and A.~Grasso and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and G.~Hamar and D.~von Harrach and F.H.~Heinsius and R.~Heitz and F.~Herrmann and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and V.~Jary and R.~Joosten and P.~Joerg and E.~Kabuss and A.~Kerbizi and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and A.~Nagaytsev and F.~Nerling and D.~Neyret and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and N.S.~Rogacheva and M.~Roskot and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and E.~Seder and A.~Selyunin and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and A.~Srnka and D.~Steffen and M.~Stolarski and O.~Subrt and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and F.~Thibaud and A.~Thiel and F.~Tosello and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and J.~Vondra and S.~Wallner and T.~Weisrock and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and N.~Zhuravlev and M.~Ziembicki and A.~Zink}, title = {{F}irst measurement of the {S}ivers asymmetry for gluons from {SIDIS} data}, year = {2017}, eprint = {1701.02453}, note = {arXiv:1701.02453v1} }
PDF
The Sivers function describes the correlation between the transverse spin of a nucleon and the transverse motion of its partons. It was extracted from measurements of the azimuthal asymmetry of hadrons produced in semi-inclusive deep inelastic scattering of leptons off transversely polarised nucleon targets, and it turned out to be non-zero for quarks. In this letter the evaluation of the Sivers asymmetry for gluons in the same process is presented. The analysis method is based on a Monte Carlo simulation that includes three hard processes: photon-gluon fusion, QCD Compton scattering and leading-order virtual-photon absorption process. The Sivers asymmetries of the three processes are simultaneously extracted using the LEPTO event generator and a neural network approach. The method is applied to samples of events containing at least two hadrons with large transverse momentum from the COMPASS data taken with a 160 GeV/$c$ muon beam scattered off transversely polarised deuterons and protons. With a significance of more than two standard deviations a negative value is obtained for the gluon Sivers asymmetry. The result of a similar analysis for a Collins-like asymmetry for gluons is consistent with zero.
Final COMPASS results on the deuteron spin-dependent structure function $g_1^{\rm d}$ and the Bjorken sum rule
C. Adolph, M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, et al (207)
Dec 05 2016 hep-ex arXiv:1612.00620v1

@misc{1612.00620, author = {C.~Adolph and M.~Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and K.~Augsten and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and M.~Ball and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and M.~Bodlak and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and Ch.~Dreisbach and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and J.~Giarra and F.~Giordano and I.~Gnesi and M.~Gorzellik and S.~Grabmueller and A.~Grasso and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and G.~Hamar and D.~von Harrach and F.H.~Heinsius and R.~Heitz and F.~Herrmann and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and V.~Jary and R.~Joosten and P.~Joerg and E.~Kabuss and A.~Kerbizi and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and A.~Nagaytsev and F.~Nerling and D.~Neyret and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and M.~Roskot and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and E.~Seder and A.~Selyunin and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and A.~Srnka and D.~Steffen and M.~Stolarski and O.~Subrt and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and F.~Thibaud and A.~Thiel and F.~Tosello and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and J.~Vondra and S.~Wallner and T.~Weisrock and M.~Wilfert and R.~Windmolders and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and N.~Zhuravlev and M.~Ziembicki and A.~Zink}, title = {{F}inal {COMPASS} results on the deuteron spin-dependent structure function $g_1^{\rm d}$ and the {B}jorken sum rule}, year = {2016}, eprint = {1612.00620}, note = {arXiv:1612.00620v1} }
PDF
Final results are presented from the inclusive measurement of deep-inelastic polarised-muon scattering on longitudinally polarised deuterons using a $^6$LiD target. The data were taken at $160~{\rm GeV}$ beam energy and the results are shown for the kinematic range $1~({\rm GeV}/c)^2 < Q^2 < 100~({\rm GeV}/c)^2$ in photon virtuality, $0.004<x<0.7$ in the Bjorken scaling variable and $W > 4~{\rm GeV}/c^2$ in the mass of the hadronic final state. The deuteron double-spin asymmetry $A_1^{\rm d}$ and the deuteron longitudinal-spin structure function $g_1^{\rm d}$ are presented in bins of $x$ and $Q^2$. Towards lowest accessible values of $x$, $g_1^{\rm d}$ decreases and becomes consistent with zero within uncertainties. The presented final $g_1^{\rm d}$ values together with the recently published final $g_1^{\rm p}$ values of COMPASS are used to again evaluate the Bjorken sum rule and perform the QCD fit to the $g_1$ world data at next-to-leading order of the strong coupling constant. In both cases, changes in central values of the resulting numbers are well within statistical uncertainties. The flavour-singlet axial charge $a_0$, which is identified in the $\overline{\rm MS}$ renormalisation scheme with the total contribution of quark helicities to the nucleon spin, is extracted from only the COMPASS deuteron data with negligible extrapolation uncertainty: $a_0 (Q^2 = 3~({\rm GeV}/c)^2) = 0.32 \pm 0.02_{\rm stat} \pm0.04_{\rm syst} \pm 0.05_{\rm evol}$. Together with the recent results on the proton spin structure function $g_1^{\rm p}$, the results on $g_1^{\rm d}$ constitute the COMPASS legacy on the measurements of $g_1$ through inclusive spin-dependent deep inelastic scattering.
Sivers asymmetry extracted in SIDIS at the hard scale of the Drell-Yan process at COMPASS
C. Adolph, M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, et al (207)
Sep 26 2016 hep-ex hep-ph arXiv:1609.07374v2

@misc{1609.07374, author = {C.~Adolph and M.~Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and K.~Augsten and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and M.~Ball and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and M.~Bodlak and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and Ch.~Dreisbach and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and C.~Elia and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and J.~Giarra and F.~Giordano and I.~Gnesi and M.~Gorzellik and S.~Grabmueller and A.~Grasso and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and G.~Hamar and D.~von Harrach and F.H.~Heinsius and R.~Heitz and F.~Herrmann and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and V.~Jary and R.~Joosten and P.~Joerg and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and A.~Nagaytsev and F.~Nerling and D.~Neyret and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and M.~Roskot and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and E.~Seder and A.~Selyunin and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and F.~Sozzi and A.~Srnka and D.~Steffen and M.~Stolarski and O.~Subrt and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and F.~Thibaud and A.~Thiel and F.~Tosello and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and J.~Vondra and S.~Wallner and T.~Weisrock and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and N.~Zhuravlev and M.~Ziembicki and A.~Zink}, title = {{S}ivers asymmetry extracted in {SIDIS} at the hard scale of the {D}rell-{Y}an process at {COMPASS}}, year = {2016}, eprint = {1609.07374}, doi = {10.1016/j.physletb.2017.04.042}, note = {arXiv:1609.07374v2} }
PDF
Proton transverse-spin azimuthal asymmetries are extracted from the COMPASS 2010 semi-inclusive hadron measurements in deep inelastic muon-nucleon scattering in those four regions of the photon virtuality $Q^2$, which correspond to the four regions of the di-muon mass $\sqrt{Q^2}$ used in the ongoing analysis of the COMPASS Drell-Yan measurements. This allows for a future direct comparison of the nucleon transverse-momentum-dependent parton distribution functions extracted from these two alternative measurements. Various two-dimensional kinematic dependences are presented for the azimuthal asymmetries induced by the Sivers transverse-momentum-dependent parton distribution function. The integrated Sivers asymmetries are found to be positive with an accuracy that appears to be sufficient to test the sign change of the Sivers function predicted by Quantum Chromodynamics.
Azimuthal asymmetries of charged hadrons produced in high-energy muon scattering off longitudinally polarised deuterons
C. Adolph, M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, et al (205)
Sep 21 2016 hep-ex hep-ph arXiv:1609.06062v2

@misc{1609.06062, author = {C.~Adolph and M.~Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and K.~Augsten and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and M.~Ball and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and M.~Bodlak and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and Ch.~Dreisbach and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and J.~Giarra and F.~Giordano and I.~Gnesi and M.~Gorzellik and S.~Grabmueller and A.~Grasso and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and G.~Hamar and D.~von Harrach and F.H.~Heinsius and R.~Heitz and F.~Herrmann and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and V.~Jary and R.~Joosten and P.~Joerg and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and A.~Nagaytsev and F.~Nerling and D.~Neyret and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and M.~Roskot and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and E.~Seder and A.~Selyunin and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and A.~Srnka and D.~Steffen and M.~Stolarski and O.~Subrt and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and F.~Thibaud and A.~Thiel and F.~Tosello and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and J.~Vondra and S.~Wallner and T.~Weisrock and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and N.~Zhuravlev and M.~Ziembicki and A.~Zink}, title = {{A}zimuthal asymmetries of charged hadrons produced in high-energy muon scattering off longitudinally polarised deuterons}, year = {2016}, eprint = {1609.06062}, note = {arXiv:1609.06062v2} }
PDF
Single hadron azimuthal asymmetries of positive and negative hadrons produced in muon semi-inclusive deep inelastic scattering off longitudinally polarised deuterons are determined using the 2006 COMPASS data and also combined all deuteron COMPASS data. For each hadron charge, the dependence of the azimuthal asymmetry on the hadron azimuthal angle $\phi$ is obtained by means of a five-parameter fitting function that besides a $\phi$-independent term includes four modulations predicted by theory: $\sin\phi$, $\sin 2 \phi$, $\sin 3\phi$ and $\cos\phi$. The amplitudes of the five terms have been extracted, first, for the hadrons in the whole available kinematic region. In further fits, performed for hadrons from a restricted kinematic region, the $\phi$-dependence is determined as a function of one of three variables (Bjorken-$x$, fractional energy of virtual photon taken by the outgoing hadron and hadron transverse momentum), while disregarding the others. Except the $\phi$-independent term, all the modulation amplitudes are very small, and no clear kinematic dependence could be observed within experimental uncertainties.
Multiplicities of charged kaons from deep-inelastic muon scattering off an isoscalar target
C. Adolph, J. Agarwala, M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, et al (207)
Aug 25 2016 hep-ex nucl-ex arXiv:1608.06760v1

@misc{1608.06760, author = {C.~Adolph and J.~Agarwala and M.~Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and K.~Augsten and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and M.~Ball and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and M.~Bodlak and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and L.~Capozza and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and Ch.~Dreisbach and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and F.~Giordano and I.~Gnesi and M.~Gorzellik and S.~Grabmueller and A.~Grasso and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and G.~Hamar and D.~von Harrach and F.H.~Heinsius and R.~Heitz and F.~Herrmann and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and V.~Jary and R.~Joosten and P.~Joeorg and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and A.~Nagaytsev and F.~Nerling and D.~Neyret and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and M.~Roskot and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and E.~Seder and A.~Selyunin and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and A.~Srnka and D.~Steffen and M.~Stolarski and O.~Subrt and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and F.~Thibaud and A.~Thiel and F.~Tosello and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and J.~Vondra and S.~Wallner and T.~Weisrock and M.~Wilfert and R.~Windmolders and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and N.~Zhuravlev and M.~Ziembicki and A.~Zink}, title = {{M}ultiplicities of charged kaons from deep-inelastic muon scattering off an isoscalar target}, year = {2016}, eprint = {1608.06760}, note = {arXiv:1608.06760v1} }
PDF
Precise measurements of charged-kaon multiplicities in deep inelastic scattering were performed. The results are presented in three-dimensional bins of the Bjorken scaling variable x, the relative virtual-photon energy y, and the fraction z of the virtual-photon energy carried by the produced hadron. The data were obtained by the COMPASS Collaboration by scattering 160 GeV muons off an isoscalar 6 LiD target. They cover the kinematic domain 1 (GeV/c)2 < Q2 < 60 (GeV/c)^2 in the photon virtuality, 0.004 < x < 0.4, 0.1 < y < 0.7, 0.20 < z < 0.85, and W > 5 GeV/c^2 in the invariant mass of the hadronic system. The results from the sum of the z-integrated K+ and K- multiplicities at high x point to a value of the non-strange quark fragmentation function larger than obtained by the earlier DSS fit.
Exclusive $\omega$ meson muoproduction on transversely polarised protons
C. Adolph, J. Agarwala, M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, et al (209)
Jun 14 2016 hep-ex nucl-ex arXiv:1606.03725v2

@misc{1606.03725, author = {C.~Adolph and J.~Agarwala and M.~Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and F.~Giordano and I.~Gnesi and M.~Gorzellik and S.~Grabmueller and A.~Grasso and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and D.~von Harrach and R.~Hashimoto and F.H.~Heinsius and R.~Heitz and F.~Herrmann and F.~Hinterberger and N.~Horikawa and N.~dHose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and R.~Joosten and P.~Joerg and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and Y.-S.~Lian and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and C.~Marchand and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and M.~Meyer and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and P.~Montuenga and A.~Nagaytsev and F.~Nerling and D.~Neyret and V.I.~Nikolaenko and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and D.V.~Peshekhonov and N.~Pierre and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and M.~Roskot and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and S.~Schopferer and E.~Seder and A.~Selyunin and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and F.~Sozzi and A.~Srnka and D.~Steffen and M.~Stolarski and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and F.~Thibaud and F.~Tosello and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and J.~Vondra and S.~Wallner and T.~Weisrock and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{E}xclusive $\omega$ meson muoproduction on transversely polarised protons}, year = {2016}, eprint = {1606.03725}, doi = {10.1016/j.nuclphysb.2016.12.015}, note = {arXiv:1606.03725v2} }
PDF
Exclusive production of $\omega$ mesons was studied at the COMPASS experiment by scattering $160~\mathrm{GeV}/\mathit{c}$ muons off transversely polarised protons. Five single-spin and three double-spin azimuthal asymmetries were measured in the range of photon virtuality $1~(\mathrm{GeV}/\mathit{c})^2 < Q^2 < 10~(\mathrm{GeV}/\mathit{c})^2$, Bjorken scaling variable $0.003 < x_{\mathit{Bj}} < 0.3$ and transverse momentum squared of the $\omega$ meson $0.05~(\mathrm{GeV}/\mathit{c})^2 < p_{T}^{2} < 0.5~(\mathrm{GeV}/\mathit{c})^2$. The measured asymmetries are sensitive to the nucleon helicity-flip Generalised Parton Distributions (GPD) $E$ that are related to the orbital angular momentum of quarks, the chiral-odd GPDs $H_{T}$ that are related to the transversity Parton Distribution Functions, and the sign of the $\pi\omega$ transition form factor. The results are compared to recent calculations of a GPD-based model.
Multiplicities of charged pions and unidentified charged hadrons from deep-inelastic scattering of muons off an isoscalar target
C. Adolph, J. Agarwala, M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, et al (208)
Apr 12 2016 hep-ex nucl-ex arXiv:1604.02695v2

@misc{1604.02695, author = {C.~Adolph and J.~Agarwala and M.~Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and L.~Capozza and W.-C.~Chang and C.~Chatterjee and M.~Chiosso and I.~Choi and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and F.~Giordano and I.~Gnesi and M.~Gorzellik and S.~Grabmueller and A.~Grasso and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and D.~von Harrach and R.~Hashimoto and F.H.~Heinsius and R.~Heitz and F.~Herrmann and F.~Hinterberger and N.~Horikawa and N.~dHose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and R.~Joosten and P.~Joerg and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and R.~Kuhn and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and C.~Marchand and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and M.~Mikhasenko and E.~Mitrofanov and N.~Mitrofanov and Y.~Miyachi and P.~Montuenga and A.~Nagaytsev and F.~Nerling and D.~Neyret and V.I.~Nikolaenko and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and D.V.~Peshekhonov and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and M.~Roskot and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and S.~Schopferer and E.~Seder and A.~Selyunin and O.Yu.~Shevchenko and D.~Steffen and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and F.~Sozzi and A.~Srnka and M.~Stolarski and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and F.~Thibaud and F.~Tosello and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and J.~Vondra and T.~Weisrock and M.~Wilfert and R.~Windmolders and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{M}ultiplicities of charged pions and unidentified charged hadrons from deep-inelastic scattering of muons off an isoscalar target}, year = {2016}, eprint = {1604.02695}, note = {arXiv:1604.02695v2} }
PDF
Multiplicities of charged pions and unidentified hadrons produced in deep-inelastic scattering were measured in bins of the Bjorken scaling variable $x$, the relative virtual-photon energy $y$ and the relative hadron energy $z$. Data were obtained by the COMPASS Collaboration using a 160 GeV muon beam and an isoscalar target ($^6$LiD). They cover the kinematic domain in the photon virtuality $Q^2$ > 1(GeV/c$)^2$, $0.004 < x < 0.4$, $0.2 < z < 0.85$ and $0.1 < y < 0.7$. In addition, a leading-order pQCD analysis was performed using the pion multiplicity results to extract quark fragmentation functions.
Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data
C. Adolph, M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E. R. Bielert, et al (201)
Dec 17 2015 hep-ex hep-ph arXiv:1512.05053v2

@misc{1512.05053, author = {C.~Adolph and M.~Aghasyan and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and N.V.~Anfimov and V.~Anosov and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and W.-C.~Chang and M.~Chiosso and I.~Choi and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and F.~Giordano and I.~Gnesi and M.~Gorzellik and S.~Grabmueller and A.~Grasso and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and D.~von Harrach and R.~Hashimoto and F.H.~Heinsius and R.~Heitz and F.~Herrmann and F.~Hinterberger and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and R.~Joosten and P.~Joerg and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.M.~Kouznetsov and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and Y.~Kulinich and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and C.~Marchand and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.V.~Meshcheryakov and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and M.~Mikhasenko and Y.~Miyachi and P.~Montuenga and A.~Nagaytsev and F.~Nerling and D.~Neyret and V.I.~Nikolaenko and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and D.V.~Peshekhonov and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and M.~Roskot and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rybnikov and A.~Rychter and R.~Salac and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and T.~Sawada and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and S.~Schopferer and E.~Seder and A.~Selyunin and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and J.~Smolik and F.~Sozzi and A.~Srnka and M.~Stolarski and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and M.~Tasevsky and S.~Tessaro and F.~Tessarotto and F.~Thibaud and F.~Tosello and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and J.~Vondra and T.~Weisrock and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and P.~Zavada and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{L}eading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data}, year = {2015}, eprint = {1512.05053}, note = {arXiv:1512.05053v2} }
PDF
Using a novel analysis technique, the gluon polarisation in the nucleon is re-evaluated using the longitudinal double-spin asymmetry measured in the cross section of semi-inclusive single-hadron muoproduction with photon virtuality $Q^2>1~({\rm GeV}/c)^2$. The data were obtained by the COMPASS experiment at CERN using a 160 GeV/$c$ polarised muon beam impinging on a polarised $^6$LiD target. By analysing the full range in hadron transverse momentum $p_{\rm T}$, the different $p_{\rm T}$-dependences of the underlying processes are separated using a neural-network approach. In the absence of pQCD calculations at next-to-leading order in the selected kinematic domain, the gluon polarisation $\Delta g/g$ is evaluated at leading order in pQCD at a hard scale of $\mu^2= \langle Q^2 \rangle = 3 ({\rm GeV}/c)^2$. It is determined in three intervals of the nucleon momentum fraction carried by gluons, $x_{\rm g}$, covering the range $0.04 \!<\! x_{ \rm g}\! <\! 0.28$~ and does not exhibit a significant dependence on $x_{\rm g}$. The average over the three intervals, $\langle \Delta g/g \rangle = 0.113 \pm 0.038_{\rm (stat.)}\pm 0.036_{\rm (syst.)}$ at $\langle x_{\rm g} \rangle \approx 0.10$, suggests that the gluon polarisation is positive in the measured $x_{\rm g}$ range.
Longitudinal double spin asymmetries in single hadron quasi-real photoproduction at high $p_T$
COMPASS Collaboration, C. Adolph, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badełek, F. Balestra, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E.R. Bielert, R. Birsa, et al (191)
Sep 14 2015 hep-ex hep-ph arXiv:1509.03526v2

@misc{1509.03526, author = {COMPASS Collaboration and C.~Adolph and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and V.~Anosov and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badełek and F.~Balestra and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.R.~Bielert and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Büchele and E.~Burtin and W.-C.~Chang and M.~Chiosso and I.~Choi and S.-U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and V.~Duic and W.~Dünnweber and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and F.~Giordano and I.~Gnesi and M.~Gorzellik and S.~Grabmüller and A.~Grasso and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and D.~von Harrach and R.~Hashimoto and F.H.~Heinsius and F.~Herrmann and F.~Hinterberger and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and R.~Joosten and P.~Jörg and E.~Kabuß and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Königsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.~Kouznetsov and M.~Krämer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and N.~Kuchinski and R.~Kuhn and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and C.~Marchand and B.~Marianski and A.~Martin and J.~Marzec and J.~Matoušek and H.~Matsuda and T.~Matsuda and G.~Meshcheryakov and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and Y.~Miyachi and P.~Montuenga and A.~Nagaytsev and F.~Nerling and D.~Neyret and V.I.~Nikolaenko and J.~Nový and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pešek and D.V.~Peshekhonov and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rychter and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schönning and S.~Schopferer and A.~Selyunin and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and F.~Sozzi and A.~Srnka and M.~Stolarski and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and S.~Tessaro and F.~Tessarotto and F.~Thibaud and F.~Tosello and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and T.~Weisrock and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{L}ongitudinal double spin asymmetries in single hadron quasi-real photoproduction at high $p_{T}$}, year = {2015}, eprint = {1509.03526}, note = {arXiv:1509.03526v2} }
PDF
We measured the longitudinal double spin asymmetries $A_{LL}$ for single hadron muo-production off protons and deuterons at photon virtuality $Q^2$ < 1(GeV/$\it c$)$^2$ for transverse hadron momenta $p_T$ in the range 0.7 GeV/$\it c$ to 4 GeV/$\it c$ . They were determined using COMPASS data taken with a polarised muon beam of 160 GeV/$\it c$ or 200 GeV/$\it c$ impinging on polarised $\mathrm{{}^6LiD}$ or $\mathrm{NH_3}$ targets. The experimental asymmetries are compared to next-to-leading order pQCD calculations, and are sensitive to the gluon polarisation $\Delta G$ inside the nucleon in the range of the nucleon momentum fraction carried by gluons $0.05 < x_g < 0.2$.
$A_{LL}(p_T)$ for single hadron photoproduction at high $p_T$
Maxime Levillain
Sep 07 2015 hep-ex hep-ph arXiv:1509.01419v1

@misc{1509.01419, author = {Maxime Levillain}, title = {${A}_{{LL}}(p_{T})$ for single hadron photoproduction at high $p_{T}$}, year = {2015}, eprint = {1509.01419}, note = {arXiv:1509.01419v1} }
PDF
In order to understand the gluon contribution to the nucleon spin, some experiments can study the production of hadrons at high transverse momemtum from lepton-nucleon or nucleon-nucleon scattering. RHIC has recently measured such double spin asymmetries $A_{LL}(p_T)$ for pion production at high center of mass energies, and inclusion of its data to global fits based on NLO collinear pQCD calculations gives some constraints on the gluon polarization in the range $0.05<x_g<0.2$. To complement these results at COMPASS range, we will present preliminary COMPASS results on double longitudinal spin asymmetries $A_{LL}(p_T)$ for single hadron production measured on deuteron and proton target at $Q^2<1$ GeV$^2$, $p_T>1$ GeV/c and center of mass energy $\sqrt{s}\approx 18$ GeV. All COMPASS data taken from 2002 to 2011 by scattering 160 GeV polarized muons on longitudinally polarized $^6$LiD and NH$_3$ targets have been used, and the number of hadrons collected with $p_T>1$ GeV/c for this analysis amounts to about 10 millions. The obtained asymmetries will be compared to theoretical predictions of at NLO without gluon resummation calculation.
Resonance Production and $\pi\pi$ S-wave in $\pi^- + p \rightarrow \pi^- \pi^- \pi^+ + p_{recoil}$ at 190 GeV/c
C. Adolph, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badełek, F. Balestra, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E.R. Bielert, R. Birsa, J. Bisplinghoff, et al (190)
Sep 04 2015 hep-ex hep-ph arXiv:1509.00992v2

@misc{1509.00992, author = {C.~Adolph and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and V.~Anosov and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badełek and F.~Balestra and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.R.~Bielert and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Büchele and E.~Burtin and W.-C.~Chang and M.~Chiosso and I.~Choi and S.U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and V.~Duic and W.~Dünnweber and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and F.~Giordano and I.~Gnesi and M.~Gorzellik and S.~Grabmüller and A.~Grasso and M.~Grosse Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and D.~von Harrach and R.~Hashimoto and F.H.~Heinsius and F.~Herrmann and F.~Hinterberger and N.~Horikawa and N.~d'Hose and C.-Y.~Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and R.~Joosten and P.~Jörg and E.~Kabuß and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Königsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.~Kouznetsov and M.~Krämer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and N.~Kuchinski and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and C.~Marchand and B.~Marianski and A.~Martin and J.~Marzec and J.~Matoušek and H.~Matsuda and T.~Matsuda and G.~Meshcheryakov and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and Y.~Miyachi and P.~Montuenga and A.~Nagaytsev and F.~Nerling and D.~Neyret and V.I.~Nikolaenko and J.~Nový and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pešek and D.V.~Peshekhonov and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rychter and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and G.~Sbrizzai and P.~Schiavon and T.~Schlüter and K.~Schmidt and H.~Schmieden and K.~Schönning and S.~Schopferer and A.~Selyunin and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and F.~Sozzi and A.~Srnka and M.~Stolarski and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and S.~Tessaro and F.~Tessarotto and F.~Thibaud and F.~Tosello and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and T.~Weisrock and M.~Wilfert and J.~ter Wolbeek and K.~Zaremba and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{R}esonance {P}roduction and $\pi\pi$ {S}-wave in $\pi^- + p \rightarrow \pi^- \pi^- \pi^+ + p_{recoil}$ at 190 {G}e{V}/c}, year = {2015}, eprint = {1509.00992}, howpublished = {Phys. Rev. D 95, 032004 (2017)}, doi = {10.1103/PhysRevD.95.032004}, note = {arXiv:1509.00992v2} }
PDF
The COMPASS collaboration has collected the currently largest data set on diffractively produced $\pi^-\pi^-\pi^+$ final states using a negative pion beam of 190 GeV/c momentum impinging on a stationary proton target. This data set allows for a systematic partial-wave analysis in 100 bins of three-pion mass, $0.5 < m_{3\pi} < 2.5$ GeV/c$^2$ , and in 11 bins of the reduced four-momentum transfer squared, $0.1 < t < 1.0$ (GeV/c)$^2$ . This two-dimensional analysis offers sensitivity to genuine one-step resonance production, i.e. the production of a state followed by its decay, as well as to more complex dynamical effects in nonresonant $3\pi$ production. In this paper, we present detailed studies on selected $3\pi$ partial waves with $J^{PC} = 0^{-+}$, $1^{++}$, $2^{-+}$, $2^{++}$, and $4^{++}$. In these waves, we observe the well-known ground-state mesons as well as a new narrow axial-vector meson $a_1(1420)$ decaying into $f_0(980) \pi$. In addition, we present the results of a novel method to extract the amplitude of the $\pi^-\pi^+$ subsystem with $I^{G}J^{PC} = 0^+ 0^{++}$ in various partial waves from the $\pi^-\pi^-\pi^+$ data. Evidence is found for correlation of the $f_0(980)$ and $f_0(1500)$ appearing as intermediate $\pi^- \pi^+$ isobars in the decay of the known $\pi(1800)$ and $\pi_2(1880)$.
Interplay among transversity induced asymmetries in hadron leptoproduction
Compass Collaboration, C. Adolph, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badelek, F. Balestra, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E. R. Bielert, R. Birsa, et al (190)
Jul 29 2015 hep-ex hep-ph arXiv:1507.07593v2

@misc{1507.07593, author = {Compass Collaboration and C.~Adolph and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and V.~Anosov and W.~Augustyniak and A.~Austregesilo and C.D.R.~Azevedo and B.~Badelek and F.~Balestra and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Büchele and E.~Burtin and W.-C.~Chang and M.~Chiosso and I.~Choi and S.U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and N.~d'Hose and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and V.~Duic and M.~Dziewiecki and A.~Efremov and C.~Elia and P.D.~Eversheim and W.~Eyrich and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and F.~Giordano and I.~Gnesi and M.~Gorzellik and S.~Grabmüller and A.~Grasso and M.~Grosse-Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and D.~von Harrach and R.~Hashimoto and F.H.~Heinsius and F.~Herrmann and F.~Hinterberger and N.~Horikawa and C.-Yu Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and P.~Jörg and R.~Joosten and E.~Kabuß and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Königsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.~Kouznetsov and M.~Krämer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and N.~Kuchinski and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and C.~Marchand and B.~Marianski and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.~Meshcheryakov and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and Y.~Miyachi and P.~Montuenga and A.~Nagaytsev and F.~Nerling and D.~Neyret and V.I.~Nikolaenko and J.~Novy and W.-D.~Nowak and G.~Nukazuka and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and G.~Pesaro and M.~Pesek and D.V.~Peshekhonov and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rychter and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schönning and S.~Schopferer and A.~Selyunin and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and F.~Sozzi and A.~Srnka and M.~Stolarski and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and J.~ter Wolbeek and S.~Tessaro and F.~Tessarotto and F.~Thibaud and F.~Tosello and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and T.~Weisrock and M.~Wilfert and K.~Zaremba and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{I}nterplay among transversity induced asymmetries in hadron leptoproduction}, year = {2015}, eprint = {1507.07593}, note = {arXiv:1507.07593v2} }
PDF
In the fragmentation of a transversely polarized quark several left-right asymmetries are possible for the hadrons in the jet. When only one unpolarized hadron is selected, it exhibits an azimuthal modulation known as Collins effect. When a pair of oppositely charged hadrons is observed, three asymmetries can be considered, a di-hadron asymmetry and two single hadron asymmetries. In lepton deep inelastic scattering on transversely polarized nucleons all these asymmetries are coupled with the transversity distribution. From the high statistics COMPASS data on oppositely charged hadron-pair production we have investigated for the first time the dependence of these three asymmetries on the difference of the azimuthal angles of the two hadrons. The similarity of transversity induced single and di-hadron asymmetries is discussed. A new analysis of the data allows to establish quantitative relationships among them, providing for the first time strong experimental indication that the underlying fragmentation mechanisms are all driven by a common physical process.
The Spin Structure Function $g_1^{\rm p}$ of the Proton and a Test of the Bjorken Sum Rule
C. Adolph, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, A. Austregesilo, C. Azevedo, B. Badelek, F. Balestra, J. Barth, G. Baum, G. R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E. R. Bielert, R. Birsa, J. Bisplinghoff, et al (187)
Apr 01 2015 hep-ex hep-ph arXiv:1503.08935v1

@misc{1503.08935, author = {C.~Adolph and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and V.~Anosov and A.~Austregesilo and C.~Azevedo and B.~Badelek and F.~Balestra and J.~Barth and G.~Baum and G.~R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and E.~Burtin and L.~Capozza and W.-C.~Chang and M.~Chiosso and I.~Choi and S.U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and V.~Duic and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and W.~Eyrich and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and E.~Fuchey and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and F.~Giordano and I.~Gnesi and M.~Gorzellik and S.~Grabmüller and A.~Grasso and M.~Grosse-Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and D.~von Harrach and R.~Hashimoto and F.H.~Heinsius and F.~Herrmann and F.~Hinterberger and N.~Horikawa and N.~d'Hose and C.-Yu Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and P.~Jörg and R.~Joosten and E.~Kabuß and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.~Kouznetsov and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and N.~Kuchinski and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and R.~Longo and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and C.~Marchand and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.~Meshcheryakov and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and Y.~Miyachi and A.~Nagaytsev and T.~Nagel and F.~Nerling and D.~Neyret and V.I.~Nikolaenko and J.~Novy and W.-D.~Nowak and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and D.V.~Peshekhonov and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and E.~Rocco and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rychter and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and S.~Schopferer and A.~Selyunin and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and F.~Sozzi and A.~Srnka and M.~Stolarski and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and J.~ter Wolbeek and S.~Tessaro and F.~Tessarotto and F.~Thibaud and F.~Tosello and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and T.~Weisrock and M.~Wilfert and K.~Zaremba and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{T}he {S}pin {S}tructure {F}unction $g_1^{\rm p}$ of the {P}roton and a {T}est of the {B}jorken {S}um {R}ule}, year = {2015}, eprint = {1503.08935}, note = {arXiv:1503.08935v1} }
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New results for the double spin asymmetry $A_1^{\rm p}$ and the proton longitudinal spin structure function $g_1^{\rm p}$ are presented. They were obtained by the COMPASS collaboration using polarised 200 GeV muons scattered off a longitudinally polarised NH$_3$ target. The data were collected in 2011 and complement those recorded in 2007 at 160\u2009GeV, in particular at lower values of $x$. They improve the statistical precision of $g_1^{\rm p}(x)$ by about a factor of two in the region $x\lesssim 0.02$. A next-to-leading order QCD fit to the $g_1$ world data is performed. It leads to a new determination of the quark spin contribution to the nucleon spin, $\Delta \Sigma$ ranging from 0.26 to 0.36, and to a re-evaluation of the first moment of $g_1^{\rm p}$. The uncertainty of $\Delta \Sigma$ is mostly due to the large uncertainty in the present determinations of the gluon helicity distribution. A new evaluation of the Bjorken sum rule based on the COMPASS results for the non-singlet structure function $g_1^{\rm NS}(x,Q^2)$ yields as ratio of the axial and vector coupling constants $|g_{\rm A}/g_{\rm V}| = 1.22 \pm 0.05~({\rm stat.}) \pm 0.10~({\rm syst.})$, which validates the sum rule to an accuracy of about 9\%.
Observation of a new narrow axial-vector meson $a_1(1420)$
C. Adolph, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, A. Austregesilo, C. Azevedo, B. Badelek, F. Balestra, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E. R. Bielert, R. Birsa, J. Bisplinghoff, M. Bodlak, et al (185)
Jan 26 2015 hep-ex arXiv:1501.05732v3

@misc{1501.05732, author = {C.~Adolph and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and V.~Anosov and A.~Austregesilo and C.~Azevedo and B.~Badelek and F.~Balestra and J.~Barth and R.~Beck and Y.~Bedfer and J.~Bernhard and K.~Bicker and E.~R.~Bielert and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and E.~Burtin and W.-C.~Chang and M.~Chiosso and I.~Choi and S.U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and L.~Dhara and S.V.~Donskov and N.~Doshita and W Duennweber and V.~Duic and M.~Dziewiecki and A.~Efremov and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and I.~Gnesi and M.~Gorzellik and S.~Grabmueller and A.~Grasso and M.~Grosse-Perdekamp and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~Hahne and D.~von Harrach and R.~Hashimoto and F.H.~Heinsius and F.~Herrmann and F.~Hinterberger and N.~Horikawa and N.~d'Hose and C.-Yu Hsieh and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and P.~Joerg and R.~Joosten and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.~Kouznetsov and M.~Kraemer and P.~Kremser and F.~Krinner and Z.V.~Kroumchtein and N.~Kuchinski and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and A.~Maggiora and A.~Magnon and N.~Makins and N.~Makke and G.K.~Mallot and C.~Marchand and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.~Meshcheryakov and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and Y.~Miyachi and A.~Nagaytsev and T.~Nagel and F.~Nerling and D.~Neyret and V.I.~Nikolaenko and J.~Novy and W.-D.~Nowak and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and D.~Panzieri and B.~Parsamyan and S.~Paul and J.-C.~Peng and F.~Pereira and M.~Pesek and D.V.~Peshekhonov and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and C.~Riedl and E.~Rocco and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rychter and V.D.~Samoylenko and A.~Sandacz and C.~Santos and S.~Sarkar and I.A.~Savin and G.~Sbrizzai and P.~Schiavon and K.~Schmidt and H.~Schmieden and K.~Schoenning and S.~Schopferer and T.~Schlueter and A.~Selyunin and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and F.~Sozzi and A.~Srnka and M.~Stolarski and M.~Sulc and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and J.~ter Wolbeek and S.~Tessaro and F.~Tessarotto and F.~Thibaud and V.~Tskhay and S.~Uhl and J.~Veloso and M.~Virius and S.~Wallner and T.~Weisrock and M.~Wilfert and K.~Zaremba and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{O}bservation of a new narrow axial-vector meson $a_1(1420)$}, year = {2015}, eprint = {1501.05732}, howpublished = {Phys. Rev. Lett. 115, 082001 (2015)}, doi = {10.1103/PhysRevLett.115.082001}, note = {arXiv:1501.05732v3} }
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The COMPASS collaboration at CERN has measured diffractive dissociation of 190 GeV/$c$ pions into the $\pi^-\pi^-\pi^+$ final state using a stationary hydrogen target. A partial-wave analysis (PWA) was performed in bins of $3\pi$ mass and four-momentum transfer using the isobar model and the so far largest PWA model consisting of 88 waves. A narrow $J^{PC} = 1^{++}$ signal is observed in the $f_0(980)\,\pi$ channel. We present a resonance-model study of a subset of the spin-density matrix selecting $3\pi$ states with $J^{PC} = 2^{++}$ and $4^{++}$ decaying into $\rho(770)\,\pi$ and with $J^{PC} = 1^{++}$ decaying into $f_0(980)\,\pi$. We identify a new $a_1$ meson with mass $(1414^{+15}_{-13})$ MeV/$c^2$ and width $(153^{+8}_{-23})$ MeV/$c^2$. Within the final states investigated in our analysis, we observe the new $a_1(1420)$ decaying only into $f_0(980)\,\pi$, suggesting its exotic nature.
The COMPASS Setup for Physics with Hadron Beams
Ph. Abbon, C. Adolph, R. Akhunzyanov, Yu. Alexandrov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, A. Austregesilo, B. Badelek, F. Balestra, J. Barth, G. Baum, R. Beck, Y. Bedfer, A. Berlin, J. Bernhard, K. Bicker, E.R. Bielert, et al (212)
Oct 08 2014 physics.ins-det hep-ex arXiv:1410.1797v1

@misc{1410.1797, author = {Ph.~Abbon and C.~Adolph and R.~Akhunzyanov and Yu.~Alexandrov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and V.~Anosov and A.~Austregesilo and B.~Badelek and F.~Balestra and J.~Barth and G.~Baum and R.~Beck and Y.~Bedfer and A.~Berlin and J.~Bernhard and K.~Bicker and E.R.~Bielert and J.~Bieling and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and E.~Burtin and L.~Capozza and P.~Ciliberti and M.~Chiosso and S.U.~Chung and A.~Cicuttin and M.~Colantoni and D.~Cotte and M.L.~Crespo and Q.~Curiel and T.~Dafni and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and D.~Desforge and A.M.~Dinkelbach and S.V.~Donskov and N.~Doshita and V.~Duic and W.~Duennweber and D.~Durand and M.~Dziewiecki and A.~Efremov and C.~Elia and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and L.~Gatignon and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and R.~Geyer and A.~Giganon and I.~Gnesi and B.~Gobbo and S.~Goertz and M.~Gorzellik and S.~Grabmueller and A.~Grasso and M.~Gregori and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~von Harrach and D.~Hahne and R.~Hashimoto and F.H.~Heinsius and F.~Herrmann and F.~Hinterberger and Ch.~Hoeppner and N.~Horikawa and N.~d'Hose and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and P.~Jasinski and P.~Joerg and R.~Joosten and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.~Kouznetsov and M.~Kraemer and Z.V.~Kroumchtein and N.~Kuchinski and R.~Kuhn and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and A.~Maggiora and A.~Magnon and N.~Makke and G.K.~Mallot and C.~Marchand and J.~Marroncle and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.~Menon and G.~Meshcheryakov and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and Y.~Miyachi and M.A.~Moinester and A.~Nagaytsev and T.~Nagel and F.~Nerling and S.~Neubert and D.~Neyret and V.I.~Nikolaenko and J.~Novy and W.-D.~Nowak and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and R.~Panknin and D.~Panzieri and B.~Parsamyan and S.~Paul and G.~Pesaro and V.~Pesaro and D.V.~Peshekhonov and C.~Pires and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and J-M.~Reymond and E.~Rocco and N.S.~Rossiyskaya and J.-Y.~Rousse and D.I.~Ryabchikov and A.~Rychter and A.~Samartsev and V.D.~Samoylenko and A.~Sandacz and S.~Sarkar and I.A.~Savin and G.~Sbrizzai and P.~Schiavon and C.~Schill and T.~Schlueter and K.~Schmidt and H.~Schmieden and K.~Schoenning and S.~Schopferer and M.~Schott and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and S.~Sosio and F.~Sozzi and A.~Srnka and L.~Steiger and M.~Stolarski and M.~Sulc and R.~Sulej and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and J.~ter Wolbeek and S.~Tessaro and F.~Tessarotto and F.~Thibaud and V.~Tskhay and S.~Uhl and I.~Uman and M.~Virius and L.~Wang and T.~Weisrock and Q.~Weitzel and M.~Wilfert and R.~Windmolders and H.~Wollny and K.~Zaremba and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{T}he {COMPASS} {S}etup for {P}hysics with {H}adron {B}eams}, year = {2014}, eprint = {1410.1797}, note = {arXiv:1410.1797v1} }
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The main characteristics of the COMPASS experimental setup for physics with hadron beams are described. This setup was designed to perform exclusive measurements of processes with several charged and/or neutral particles in the final state. Making use of a large part of the apparatus that was previously built for spin structure studies with a muon beam, it also features a new target system as well as new or upgraded detectors. The hadron setup is able to operate at the high incident hadron flux available at CERN. It is characterised by large angular and momentum coverages, large and nearly flat acceptances, and good two and three-particle mass resolutions. In 2008 and 2009 it was successfully used with positive and negative hadron beams and with liquid hydrogen and solid nuclear targets. This article describes the new and upgraded detectors and auxiliary equipment, outlines the reconstruction procedures used, and summarises the general performance of the setup.
Odd and Even Partial Waves of $\eta\pi^-$ and $\eta'\pi^-$ in $\pi^-p\to\eta^{(\prime)}\pi^-p$ at $191\,\textrm{GeV}/c$
C. Adolph, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, A. Austregesilo, B. Badelek, F. Balestra, J. Barth, G. Baum, R. Beck, Y. Bedfer, A. Berlin, J. Bernhard, K. Bicker, E. R. Bielert, J. Bieling, R. Birsa, et al (189)
Aug 20 2014 hep-ex nucl-ex arXiv:1408.4286v1

@misc{1408.4286, author = {C.~Adolph and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and V.~Anosov and A.~Austregesilo and B.~Badelek and F.~Balestra and J.~Barth and G.~Baum and R.~Beck and Y.~Bedfer and A.~Berlin and J.~Bernhard and K.~Bicker and E.~R.~Bielert and J.~Bieling and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and E.~Burtin and L.~Capozza and M.~Chiosso and S.U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and S.V.~Donskov and N.~Doshita and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and C.~Elia and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and A.~Filin and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and R.~Geyer and I.~Gnesi and B.~Gobbo and S.~Goertz and M.~Gorzellik and S.~Grabmueller and A.~Grasso and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~von Harrach and D.~Hahne and R.~Hashimoto and F.H.~Heinsius and F.~Herrmann and F.~Hinterberger and Ch.~Hoeppner and N.~Horikawa and N.~d'Hose and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and P.~Jasinski and P.~Joerg and R.~Joosten and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.~Kouznetsov and M.~Kraemer and Z.V.~Kroumchtein and N.~Kuchinski and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and A.~Maggiora and A.~Magnon and N.~Makke and G.K.~Mallot and C.~Marchand and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.~Meshcheryakov and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and Y.~Miyachi and A.~Nagaytsev and T.~Nagel and F.~Nerling and S.~Neubert and D.~Neyret and V.I.~Nikolaenko and J.~Novy and W.-D.~Nowak and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and R.~Panknin and D.~Panzieri and B.~Parsamyan and S.~Paul and D.V.~Peshekhonov and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and E.~Rocco and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rychter and V.D.~Samoylenko and A.~Sandacz and S.~Sarkar and I.A.~Savin and G.~Sbrizzai and P.~Schiavon and C.~Schill and T.~Schlueter and K.~Schmidt and H.~Schmieden and K.~Schoenning and S.~Schopferer and M.~Schott and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and S.~Sosio and F.~Sozzi and A.~Srnka and L.~Steiger and M.~Stolarski and M.~Sulc and R.~Sulej and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and J.~ter Wolbeek and S.~Tessaro and F.~Tessarotto and F.~Thibaud and S.~Uhl and I.~Uman and M.~Virius and L.~Wang and T.~Weisrock and M.~Wilfert and R.~Windmolders and H.~Wollny and K.~Zaremba and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{O}dd and {E}ven {P}artial {W}aves of $\eta\pi^-$ and $\eta'\pi^-$ in $\pi^-p\to\eta^{(\prime)}\pi^-p$ at $191\,\textrm{{G}e{V}}/c$}, year = {2014}, eprint = {1408.4286}, note = {arXiv:1408.4286v1} }
PDF
Exclusive production of $\eta\pi^-$ and $\eta'\pi^-$ has been studied with a $191\,\textrm{GeV}/c$ $\pi^-$ beam impinging on a hydrogen target at COMPASS (CERN). Partial-wave analyses reveal different odd/even angular momentum ($L$) characteristics in the inspected invariant mass range up to $3\,\textrm{GeV}/c^2$. A striking similarity between the two systems is observed for the $L=2,4,6$ intensities (scaled by kinematical factors) and the relative phases. The known resonances $a_2(1320)$ and $a_4(2040)$ are in line with this similarity. In contrast, a strong enhancement of $\eta'\pi^-$ over $\eta\pi^-$ is found for the $L=1,3,5$ waves, which carry non-$q\bar q$ quantum numbers. The $L=1$ intensity peaks at $1.7\,\textrm{GeV}/c^2$ in $\eta'\pi^-$ and at $1.4\,\textrm{GeV}/c^2$ in $\eta\pi^-$, the corresponding phase motions with respect to $L=2$ are different.
Collins and Sivers asymmetries in muonproduction of pions and kaons off transversely polarised proton
C. Adolph, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, A. Austregesilo, B. Badelek, F. Balestra, J. Barth, G. Baum, R. Beck, Y. Bedfer, A. Berlin, J. Bernhard, K. Bicker, E. R. Bielert, J. Bieling, R. Birsa, et al (189)
Aug 20 2014 hep-ex arXiv:1408.4405v1

@misc{1408.4405, author = {C.~Adolph and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and V.~Anosov and A.~Austregesilo and B.~Badelek and F.~Balestra and J.~Barth and G.~Baum and R.~Beck and Y.~Bedfer and A.~Berlin and J.~Bernhard and K.~Bicker and E.~R.~Bielert and J.~Bieling and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and E.~Burtin and L.~Capozza and M.~Chiosso and S.U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and S.V.~Donskov and N.~Doshita and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and C.~Elia and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and A.~Filin and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and R.~Geyer and I.~Gnesi and B.~Gobbo and S.~Goertz and M.~Gorzellik and S.~Grabmueller and A.~Grasso and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~von Harrach and D.~Hahne and R.~Hashimoto and F.H.~Heinsius and F.~Herrmann and F.~Hinterberger and Ch.~Hoeppner and N.~Horikawa and N.~d'Hose and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and P.~Jasinski and P.~Joerg and R.~Joosten and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.~Kouznetsov and M.~Kraemer and Z.V.~Kroumchtein and N.~Kuchinski and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and A.~Maggiora and A.~Magnon and N.~Makke and G.K.~Mallot and C.~Marchand and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.~Meshcheryakov and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and Y.~Miyachi and A.~Nagaytsev and T.~Nagel and F.~Nerling and S.~Neubert and D.~Neyret and V.I.~Nikolaenko and J.~Novy and W.-D.~Nowak and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and R.~Panknin and D.~Panzieri and B.~Parsamyan and S.~Paul and D.V.~Peshekhonov and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and E.~Rocco and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rychter and V.D.~Samoylenko and A.~Sandacz and S.~Sarkar and I.A.~Savin and G.~Sbrizzai and P.~Schiavon and C.~Schill and T.~Schlueter and K.~Schmidt and H.~Schmieden and K.~Schoenning and S.~Schopferer and M.~Schott and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and S.~Sosio and F.~Sozzi and A.~Srnka and L.~Steiger and M.~Stolarski and M.~Sulc and R.~Sulej and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and J.~ter Wolbeek and S.~Tessaro and F.~Tessarotto and F.~Thibaud and S.~Uhl and I.~Uman and M.~Virius and L.~Wang and T.~Weisrock and M.~Wilfert and R.~Windmolders and H.~Wollny and K.~Zaremba and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{C}ollins and {S}ivers asymmetries in muonproduction of pions and kaons off transversely polarised proton}, year = {2014}, eprint = {1408.4405}, note = {arXiv:1408.4405v1} }
PDF
Measurements of the Collins and Sivers asymmetries for charged pions and charged and neutral kaons produced in semi-inclusive deep-inelastic scattering of high energy muons off transversely polarised protons are presented. The results were obtained using all the available COMPASS proton data, which were taken in the years 2007 and 2010. The Collins asymmetries exhibit in the valence region a non-zero signal for pions and there are hints of non-zero signal also for kaons. The Sivers asymmetries are found to be positive for positive pions and kaons and compatible with zero otherwise.
Search for exclusive photoproduction of Z$_c^{\pm}$(3900) at COMPASS
C. Adolph, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, A. Austregesilo, B. Badelek, F. Balestra, J. Barth, G. Baum, R. Beck, Y. Bedfer, A. Berlin, J. Bernhard, K. Bicker, E. R. Bielert, J. Bieling, R. Birsa, et al (189)
Jul 24 2014 hep-ex arXiv:1407.6186v1

@misc{1407.6186, author = {C.~Adolph and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and V.~Anosov and A.~Austregesilo and B.~Badelek and F.~Balestra and J.~Barth and G.~Baum and R.~Beck and Y.~Bedfer and A.~Berlin and J.~Bernhard and K.~Bicker and E.~R.~Bielert and J.~Bieling and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and E.~Burtin and L.~Capozza and M.~Chiosso and S.U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and S.V.~Donskov and N.~Doshita and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and C.~Elia and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and A.~Filin and M.~Finger and M.~Finger jr.~and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and R.~Geyer and I.~Gnesi and B.~Gobbo and S.~Goertz and M.~Gorzellik and S.~Grabmueller and A.~Grasso and B.~Grube and T.~Grussenmeyer and A.~Guskov and F.~Haas and D.~von Harrach and D.~Hahne and R.~Hashimoto and F.H.~Heinsius and F.~Herrmann and F.~Hinterberger and Ch.~Hoeppner and N.~Horikawa and N.~d'Hose and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and P.~Jasinski and P.~Joerg and R.~Joosten and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.~Kouznetsov and M.~Kraemer and Z.V.~Kroumchtein and N.~Kuchinski and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and A.~Maggiora and A.~Magnon and N.~Makke and G.K.~Mallot and C.~Marchand and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.~Meshcheryakov and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and Y.~Miyachi and A.~Nagaytsev and T.~Nagel and F.~Nerling and S.~Neubert and D.~Neyret and V.I.~Nikolaenko and J.~Novy and W.-D.~Nowak and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and R.~Panknin and D.~Panzieri and B.~Parsamyan and S.~Paul and D.V.~Peshekhonov and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and E.~Rocco and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rychter and V.D.~Samoylenko and A.~Sandacz and S.~Sarkar and I.A.~Savin and G.~Sbrizzai and P.~Schiavon and C.~Schill and T.~Schlueter and K.~Schmidt and H.~Schmieden and K.~Schoenning and S.~Schopferer and M.~Schott and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and S.~Sosio and F.~Sozzi and A.~Srnka and L.~Steiger and M.~Stolarski and M.~Sulc and R.~Sulej and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and J.~ter Wolbeek and S.~Tessaro and F.~Tessarotto and F.~Thibaud and S.~Uhl and I.~Uman and M.~Virius and L.~Wang and T.~Weisrock and M.~Wilfert and R.~Windmolders and H.~Wollny and K.~Zaremba and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{S}earch for exclusive photoproduction of {Z}$_c^{\pm}$(3900) at {COMPASS}}, year = {2014}, eprint = {1407.6186}, note = {arXiv:1407.6186v1} }
PDF
A search for the exclusive production of the $Z_c^{\pm}(3900)$ hadron by virtual photons has been performed in the channel $Z_c^{\pm}(3900)\rightarrow J/\psi \pi^{\pm}$. The data cover the range from 7 GeV to 19 GeV in the centre-of-mass energy of the photon-nucleon system. The full set of the COMPASS data set collected with a muon beam between 2002 and 2011 has been used. An upper limit for the ratio $BR(Z_c^{\pm}(3900)\rightarrow J/\psi \pi^{\pm} )\times \sigma_{ \gamma~N \rightarrow Z_c^{\pm}(3900)~ N} /\sigma_{\gamma~N \rightarrow J/\psi~ N}$ of $3.7\times10^{-3}$ has been established at the confidence level of 90%.
Spin alignment and violation of the OZI rule in exclusive $\omega$ and $\phi$ production in pp collisions
C. Adolph, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, A. Austregesilo, B. Badelek, F. Balestra, J. Barth, G. Baum, R. Beck, Y. Bedfer, A. Berlin, J. Bernhard, K. Bicker, J. Bieling, R. Birsa, J. Bisplinghoff, et al (189)
May 27 2014 hep-ex nucl-ex arXiv:1405.6376v1

@misc{1405.6376, author = {C.~Adolph and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and V.~Anosov and A.~Austregesilo and B.~Badelek and F.~Balestra and J.~Barth and G.~Baum and R.~Beck and Y.~Bedfer and A.~Berlin and J.~Bernhard and K.~Bicker and J.~Bieling and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and E.~Burtin and L.~Capozza and M.~Chiosso and S.U.~Chung and A.~Cicuttin and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and S.V.~Donskov and N.~Doshita and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and C.~Elia and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and A.~Filin and M.~Finger and r.~M.~Finger and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and R.~Geyer and I.~Gnesi and B.~Gobbo and S.~Goertz and M.~Gorzellik and S.~Grabmueller and A.~Grasso and B.~Grube and T.~Grussenmeyer and A.~Guskov and T.~Guthoerl and F.~Haas and D.~von Harrach and D.~Hahne and R.~Hashimoto and F.H.~Heinsius and F.~Herrmann and F.~Hinterberger and h.~Hoeppner and N.~Horikawa and N.~d'Hose and S.~Huber and S.~Ishimoto and A.~Ivanov and u.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and P.~Jasinski and P.~Joerg and R.~Joosten and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and u.A.~Khokhlov and u.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.~Kouznetsov and M.~Kraemer and Z.V.~Kroumchtein and N.~Kuchinski and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and A.~Maggiora and A.~Magnon and N.~Makke and G.K.~Mallot and C.~Marchand and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.~Meshcheryakov and W.~Meyer and T.~Michigami and u.V.~Mikhailov and Y.~Miyachi and A.~Nagaytsev and T.~Nagel and F.~Nerling and S.~Neubert and D.~Neyret and V.I.~Nikolaenko and J.~Novy and W.-D.~Nowak and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and R.~Panknin and D.~Panzieri and B.~Parsamyan and S.~Paul and D.~Peshekhonov and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and E.~Rocco and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rychter and V.D.~Samoylenko and A.~Sandacz and S.~Sarkar and I.A.~Savin and G.~Sbrizzai and P.~Schiavon and C.~Schill and T.~Schlueter and K.~Schmidt and H.~Schmieden and K.~Schoenning and S.~Schopferer and M.~Schott and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and S.~Sosio and F.~Sozzi and A.~Srnka and L.~Steiger and M.~Stolarski and M.~Sulc and R.~Sulej and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and J.~ter Wolbeek and S.~Tessaro and F.~Tessarotto and F.~Thibaud and S.~Uhl and I.~Uman and M.~Virius and L.~Wang and T.~Weisrock and M.~Wilfert and R.~Windmolders and H.~Wollny and K.~Zaremba and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{S}pin alignment and violation of the {OZI} rule in exclusive $\omega$ and $\phi$ production in pp collisions}, year = {2014}, eprint = {1405.6376}, note = {arXiv:1405.6376v1} }
PDF
Exclusive production of the isoscalar vector mesons $\omega$ and $\phi$ is measured with a 190 GeV$/c$ proton beam impinging on a liquid hydrogen target. Cross section ratios are determined in three intervals of the Feynman variable $x_{F}$ of the fast proton. A significant violation of the OZI rule is found, confirming earlier findings. Its kinematic dependence on $x_{F}$ and on the invariant mass $M_{p\mathrm{V}}$ of the system formed by fast proton $p_\mathrm{fast}$ and vector meson $V$ is discussed in terms of diffractive production of $p_\mathrm{fast}V$ resonances in competition with central production. The measurement of the spin density matrix element $\rho_{00}$ of the vector mesons in different selected reference frames provides another handle to distinguish the contributions of these two major reaction types. Again, dependences of the alignment on $x_{F}$ and on $M_{p\mathrm{V}}$ are found. Most of the observations can be traced back to the existence of several excited baryon states contributing to $\omega$ production which are absent in the case of the $\phi$ meson. Removing the low-mass $M_{p\mathrm{V}}$ resonant region, the OZI rule is found to be violated by a factor of eight, independently of $x_\mathrm{F}$.
Measurement of the charged-pion polarisability
C. Adolph, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, A. Austregesilo, B. Badelek, F. Balestra, J. Barth, G. Baum, R. Beck, Y. Bedfer, A. Berlin, J. Bernhard, K. Bicker, J. Bieling, R. Birsa, J. Bisplinghoff, et al (193)
May 27 2014 hep-ex nucl-ex arXiv:1405.6377v2

@misc{1405.6377, author = {C.~Adolph and R.~Akhunzyanov and M.G.~Alexeev and G.D.~Alexeev and A.~Amoroso and V.~Andrieux and V.~Anosov and A.~Austregesilo and B.~Badelek and F.~Balestra and J.~Barth and G.~Baum and R.~Beck and Y.~Bedfer and A.~Berlin and J.~Bernhard and K.~Bicker and J.~Bieling and R.~Birsa and J.~Bisplinghoff and M.~Bodlak and M.~Boer and P.~Bordalo and F.~Bradamante and C.~Braun and A.~Bressan and M.~Buechele and E.~Burtin and L.~Capozza and M.~Chiosso and S.U.~Chung and A.~Cicuttin and M.~Colantoni and M.L.~Crespo and Q.~Curiel and S.~Dalla Torre and S.S.~Dasgupta and S.~Dasgupta and O.Yu.~Denisov and A.M.~Dinkelbach and S.V.~Donskov and N.~Doshita and V.~Duic and W.~Duennweber and M.~Dziewiecki and A.~Efremov and C.~Elia and P.D.~Eversheim and W.~Eyrich and M.~Faessler and A.~Ferrero and A.~Filin and M.~Finger and M.~jr.~Finger and H.~Fischer and C.~Franco and N.~du Fresne von Hohenesche and J.M.~Friedrich and V.~Frolov and F.~Gautheron and O.P.~Gavrichtchouk and S.~Gerassimov and R.~Geyer and I.~Gnesi and B.~Gobbo and S.~Goertz and M.~Gorzellik and S.~Grabmueller and A.~Grasso and B.~Grube and T.~Grussenmeyer and A.~Guskov and T.~Guthoerl and F.~Haas and D.~von Harrach and D.~Hahne and R.~Hashimoto and F.H.~Heinsius and F.~Herrmann and F.~Hinterberger and Ch.~Hoeppner and N.~Horikawa and N.~d'Hose and S.~Huber and S.~Ishimoto and A.~Ivanov and Yu.~Ivanshin and T.~Iwata and R.~Jahn and V.~Jary and P.~Jasinski and P.~Joerg and R.~Joosten and E.~Kabuss and B.~Ketzer and G.V.~Khaustov and Yu.A.~Khokhlov and Yu.~Kisselev and F.~Klein and K.~Klimaszewski and J.H.~Koivuniemi and V.N.~Kolosov and K.~Kondo and K.~Koenigsmann and I.~Konorov and V.F.~Konstantinov and A.M.~Kotzinian and O.~Kouznetsov and M.~Kraemer and Z.V.~Kroumchtein and N.~Kuchinski and R.~Kuhn and F.~Kunne and K.~Kurek and R.P.~Kurjata and A.A.~Lednev and A.~Lehmann and M.~Levillain and S.~Levorato and J.~Lichtenstadt and A.~Maggiora and A.~Magnon and N.~Makke and G.K.~Mallot and C.~Marchand and A.~Martin and J.~Marzec and J.~Matousek and H.~Matsuda and T.~Matsuda and G.~Meshcheryakov and W.~Meyer and T.~Michigami and Yu.V.~Mikhailov and Y.~Miyachi and M.A.~Moinester and A.~Nagaytsev and T.~Nagel and F.~Nerling and S.~Neubert and D.~Neyret and V.I.~Nikolaenko and J.~Novy and W.-D.~Nowak and A.S.~Nunes and A.G.~Olshevsky and I.~Orlov and M.~Ostrick and R.~Panknin and D.~Panzieri and B.~Parsamyan and S.~Paul and D.~Peshekhonov and S.~Platchkov and J.~Pochodzalla and V.A.~Polyakov and J.~Pretz and M.~Quaresma and C.~Quintans and S.~Ramos and C.~Regali and G.~Reicherz and E.~Rocco and N.S.~Rossiyskaya and D.I.~Ryabchikov and A.~Rychter and V.D.~Samoylenko and A.~Sandacz and S.~Sarkar and I.A.~Savin and G.~Sbrizzai and P.~Schiavon and C.~Schill and T.~Schlueter and K.~Schmidt and H.~Schmieden and K.~Schoenning and S.~Schopferer and M.~Schott and O.Yu.~Shevchenko and L.~Silva and L.~Sinha and S.~Sirtl and M.~Slunecka and S.~Sosio and F.~Sozzi and A.~Srnka and L.~Steiger and M.~Stolarski and M.~Sulc and R.~Sulej and H.~Suzuki and A.~Szabelski and T.~Szameitat and P.~Sznajder and S.~Takekawa and J.~ter Wolbeek and S.~Tessaro and F.~Tessarotto and F.~Thibaud and S.~Uhl and I.~Uman and M.~Virius and L.~Wang and T.~Weisrock and M.~Wilfert and R.~Windmolders and H.~Wollny and K.~Zaremba and M.~Zavertyaev and E.~Zemlyanichkina and M.~Ziembicki and A.~Zink}, title = {{M}easurement of the charged-pion polarisability}, year = {2014}, eprint = {1405.6377}, note = {arXiv:1405.6377v2} }
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The COMPASS collaboration at CERN has investigated pion Compton scattering, $\pi^-\gamma\rightarrow \pi^-\gamma$, at centre-of-mass energy below 3.5 pion masses. The process is embedded in the reaction $\pi^-\mathrm{Ni}\rightarrow\pi^-\gamma\;\mathrm{Ni}$, which is initiated by 190\u2009GeV pions impinging on a nickel target. The exchange of quasi-real photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, $Q^2<0.0015$\,(GeV/$c$)$^2$. From a sample of 63\u2009000 events the pion electric polarisability is determined to be $\alpha_\pi\ =\ (\,2.0\ \pm\ 0.6_{\mbox{\scriptsize stat}}\ \pm\ 0.7_{\mbox{\scriptsize syst}}\,) \times 10^{-4}\,\mbox{fm}^3$ under the assumption $\alpha_\pi=-\beta_\pi$, which relates the electric and magnetic dipole polarisabilities. It is the most precise measurement of this fundamental low-energy parameter of strong interaction, that has been addressed since long by various methods with conflicting outcomes. While this result is in tension with previous dedicated measurements, it is found in agreement with the expectation from chiral perturbation theory. An additional measurement replacing pions by muons, for which the cross-section behavior is unambigiously known, was performed for an independent estimate of the systematic uncertainty.