Standard and nonstandard comparisons of relative trace formulas

Seminar: 
Number Theory
Event time: 
Monday, January 28, 2013 - 11:30am to Sunday, January 27, 2013 - 7:00pm
Location: 
431 DL
Speaker: 
Yiannis Sakellaridis
Speaker affiliation: 
Rutgers Newark
Event description: 

The trace formula has been the most powerful and mainstream tool in automorphic forms for proving instances of Langlands functoriality, including character relations. Its generalization, the relative trace formula, has also been used to prove functoriality between spaces (more precisely: spherical homogeneous varieties), which is a generalization of functoriality for groups, including relations between periods of automorphic forms. These methods are based on what one could call standard comparisons, and those comparisons seem close to exhausting their range of applicability; I will review them using a simple example of Jacquet. Then, I will describe a simple instance of a new, nonstandard comparison which bears resemblance to Langlands’ Beyond Endoscopy project: nonstandard test functions tailored to produce L-functions, comparison via Fourier transforms and Poisson summation formulas, etc. The result is a new proof of Waldspurger’s formula relating squares of toric periods in GL(2) and central values of L-functions.