The local character expansion near a tame, semisimple element

Consider the character of an irreducible admissible representation of a p-adic reductive group. The Harish-Chandra-Howe local expansion expresses this character near a semisimple element as a linear combination of Fourier transforms of nilpotent orbital integrals. Under mild hypotheses, we describe an explicit region on which the local character expansion is valid. We assume neither that the group is connected nor that the underlying field has characteristic zero.Comment: 20 pages; final version; reference and comments updated; section and bibliography order changed; one typo correcte

Lifting representations of finite reductive groups II: Explicit conorms

Let $k$ be a field, $\tilde{G}$ a connected reductive $k$-quasisplit group, $\Gamma$ a finite group that acts on $\tilde{G}$ via $k$-automorphisms satisfying a quasi-semisimplicity condition, and $G$ the connected part of the group of $\Gamma$-fixed points of $\tilde{G}$, also assumed $k$-quasisplit. In an earlier work, the authors constructed a canonical map $\hat{\mathcal{N}}$ from the set of stable semisimple conjugacy classes in the dual $G^*(k)$ to the set of such classes in $\tilde{G}^*(k)$. We describe several situations where $\hat{\mathcal{N}}$ can be refined to an explicit function on points, or where it factors through such a function

Depth-zero base change for unramified U(2,1)

We give an explicit description of L-packets and quadratic base change for depth-zero representations of unramified unitary groups in two and three variables. We show that this base change is compatible with unrefined minimal K-types.Comment: 30 pages; uses LaTeX packages graphics (for a rotated table) and xy (for a diagram

On Kostant Sections and Topological Nilpotence

Let G denote a connected, quasi-split reductive group over a field F that is complete with respect to a discrete valuation and that has a perfect residue field. Under mild hypotheses, we produce a subset of the Lie algebra g(F) that picks out a G(F)-conjugacy class in every stable, regular, topologically nilpotent conjugacy class in g(F). This generalizes an earlier result obtained by DeBacker and one of the authors under stronger hypotheses. We then show that if F is p-adic, then the characteristic function of this set behaves well with respect to endoscopic transfer.Comment: 23 pages, accepted for publication in the Journal of the London Mathematical Societ

Duels and the Roots of Violence in Missouri

Review of: Duels and the Roots of Violence in Missouri. Steward, Dick