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Universal KZB equations: the elliptic case. (English) Zbl 1241.32011

Tschinkel, Yuri (ed.) et al., Algebra, arithmetic, and geometry. In honor of Yu. I. Manin on the occasion of his 70th birthday. Vol. I. Boston, MA: Birkhäuser (ISBN 978-0-8176-4744-5/hbk; 978-0-8176-4745-2/ebook). Progress in Mathematics 269, 165-266 (2009).
Summary: We define a universal version of the Knizhnik-Zamolodchikov-Bernard (KZB) connection in genus 1. This is a flat connection over a principal bundle on the moduli space of elliptic curves with marked points. It restricts to a flat connection on configuration spaces of points on elliptic curves, which can be used for proving the formality of the pure braid groups on genus 1 surfaces. We study the monodromy of this connection and show that it gives rise to a relation between the KZ associator and a generating series for iterated integrals of Eisenstein forms. We show that the universal KZB connection realizes as the usual KZB connection for simple Lie algebras, and that in the \(\mathfrak{sl}_n\) case this realization factors through the Cherednik algebras. This leads us to define a functor from the category of equivariant \(D\)-modules on \(\mathfrak{sl}_n\) to that of modules over the Cherednik algebra, and to compute the character of irreducible equivariant \(D\)-modules over \(\mathfrak{sl}_n\) which are supported on the nilpotent cone.
For the entire collection see [Zbl 1185.00041].

MSC:

32G34 Moduli and deformations for ordinary differential equations (e.g., Knizhnik-Zamolodchikov equation)
17B37 Quantum groups (quantized enveloping algebras) and related deformations
11F55 Other groups and their modular and automorphic forms (several variables)