Nonvanishing of L-functions, the Ramanujan Conjecture, and Families of Hecke Characters

Abstract

AbstractWe prove a nonvanishing result for families of GLn× GLn Rankin–Selberg L-functions in the critical strip, as one factor runs over twists by Hecke characters. As an application, we simplify the proof, due to Luo, Rudnick, and Sarnak, of the best known bounds towards the Generalized Ramanujan Conjecture at the infinite places for cusp forms on GLn. A key ingredient is the regularization of the units in residue classes by the use of an Arakelov ray class group.