Hopf-Hecke algebras, infinitesimal Cherednik algebras, and Dirac cohomology

Abstract

Hopf-Hecke algebras and Barbasch-Sahi algebras were defined by the first named author (2016) in order to provide a general framework for the study of Dirac cohomology. The aim of this paper is to explore new examples of these definitions and to contribute to their classification. Hopf-Hecke algebras are distinguished by an orthogonality condition and a PBW property. The PBW property for algebras such as the ones considered here has been of great interest in the literature and we extend this discussion by further results on the classification of such deformations and by a class of hitherto unexplored examples. We study infinitesimal Cherednik algebras of $G{L}_n$ as defined by Etingof, Gan, and Ginzburg in [Transform. Groups, 2005] as new examples of Hopf-Hecke algebras with a generalized Dirac cohomology. We show that they are in fact Barbasch-Sahi algebras, that is, a version of Vogan's conjecture analogous to the results of Huang and Pandžić in [J. Amer. Math. Soc., 2002] is available for them. We derive an explicit formula for the square of the Dirac operator and use it to study the finite-dimensional irreducible modules. We find that the Dirac cohomology of these modules is non-zero and that it, in fact, determines the modules uniquely.

arXiv comment34 pages. Added a more precise description of the Dirac cohomoloy of the finite-dimensional modules of the infinitesimal Cherednik algebras of GL_n, and a description of the map zeta relating central characters (Sec. 4.3). To appear in Pure Appl. Math. Q. (Kostant edition)