Semiinfinite cohomology of contragradient Weyl modules over small quantum groups

Abstract

In this paper we construct some quantum analogues of the global Cousin complex for the flag variety in positive characteristic. Just like in the positive characteristic case, we obtain some remarkable resolutions of the contragradient modules over the small quantum group. We use these resolutions to calculate semiinfinite cohomology of the small quantum group with coefficients in contragradient Weyl modules. It turns out that the described graded space of semiinfinite cohomology is naturally isomorphic to the space of distributions on the cotangent bundle of the flag variety with support in the union of conormal bundles to the Schubert cells with coefficients in the pull-back of a line bundle on the flag variety.