Endoscopy for Modular Hecke Categories
arXiv:2508.10214
Abstract
Generalizing the theory of parity sheaves on complex algebraic stacks due to Juteau-Mautner-Williamson, we develop a theory of twisted equivariant parity sheaves. We use this formalism to construct a modular incarnation of Lusztig and Yun's monodromic Hecke category. We then give two applications: (1) a modular categorification of the monodromic Hecke algebra, and (2) a monoidal equivalence between the monodromic Hecke category of parity sheaves and the ordinary Hecke category of parity sheaves on the endoscopic group.
101 pages. Many small errors and typos corrected. Exposition improved in many places. Flaw in Whittaker category section corrected with new arguments