The fundamental solution to \(\Box_b\) on quadric manifolds with nonzero eigenvalues and null variables. (English) Zbl 1537.32132
Summary: We prove sharp pointwise bounds on the complex Green operator and its derivatives on a class of embedded quadric manifolds of high codimension. In particular, we start with the class of quadrics that we previously analyzed [the authors, Trans. Am. Math. Soc., Ser. B 10, 507–541 (2023; Zbl 1517.32120)] – ones whose directional Levi forms are nondegenerate, and add in null variables. The null variables do not substantially affect the estimates or analysis at the form levels for which \(\Box_b\) is solvable and hypoelliptic. In the nonhypoelliptic degrees, however, the estimates and analysis are substantially different. In the earlier paper, when hypoellipticity of \(\Box_b\) failed, so did solvability. Here, however, we show that if there is at least one null variable, \( \Box_b\) is always solvable, and the estimates are qualitatively different than in the other cases. Namely, the complex Green operator has blow-ups off of the diagonal. We also characterize when a quadric \(M\) whose Levi form vanishes on a complex subspace admits a \(\Box_b\)-invariant change of coordinates so that \(M\) presents with a null variable.
MSC:
32V20 | Analysis on CR manifolds |
32W10 | \(\overline\partial_b\) and \(\overline\partial_b\)-Neumann operators |
Citations:
Zbl 1517.32120References:
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