# GALOIS REPRESENTATIONS AND AUTOMORPHIC FORMS SEMINAR

**Topic: **Periods Over Spherical Subgroups: An Extension of Some of the Langlands Conjectures

**Speaker: **Yiannis Sakellaridis

**Affiliation: **Member, School of Mathematics

**Date & Time: **Wednesday March 16th, 2011, 3:30pm - 4:30pm

**Location: **S-101

Periods of automorphic forms over spherical subgroups tend to: (1) distinguish images of functorial lifts and (2) give information about L-functions. This raises the following questions, given a spherical variety X=H\G: Locally, which irreducible representations admit a non-zero H-invariant functional or, equivalently, appear in the space of functions on X? Globally, can the period over H of an automorphic form on G be related to some L-value? The conjectural answer involves a "dual group" associated to X and can be seen as a generalization of part of the Langlands conjectures for the case X=a group under left and right multiplication by itself. I will describe the dual group and discuss evidence suggesting that the relative trace formula of Jacquet is the correct framework for a more precise formulation of the conjectures.