Representations of reduced enveloping algebras and cells in the affine Weyl group

Abstract

Let G be a semisimple algebraic group over an algebraically closed field of characteristic p>0, and let g be its Lie algebra. The crucial Lie algebra representations to understand are those associated with the reduced enveloping algebra U_chi(g) for a nilpotent chi in g*. We conjecture that there is a natural assignment of simple modules in a regular block to left cells in the affine Weyl group (for the dual root system) lying in the two-sided cell which corresponds to the orbit of chi in Lusztig's bijection. This should respect the action of the component group of C_G(chi) and fit naturally into Lusztig's enriched bijection involving the characters of C_G(chi). Some evidence will be described in special cases.