2014/04/30 by Valentin Blomer, Djordje Milićević · 2 citations
Mathematics · #math.NT
paper · pdf · doi:10.1007/s00039-015-0318-7
published as Geom. Funct. Anal. 25 (2015) 453-516 · 64 pages
arxiv created 2014/04/30 · arxiv updated 2020/04/28
We prove an asymptotic formula with a power saving error term for the (pure or mixed) second moment of central values of L-functions of any two (possibly equal) fixed cusp forms f, g twisted by all primitive characters modulo q, valid for all sufficiently factorable q including 99.9% of all admissible moduli. The two key ingredients are a careful spectral analysis of a potentially highly unbalanced shifted convolution problem in Hecke eigenvalues and power-saving bounds for sums of products of Kloosterman sums where the length of the sum is below the square-root threshold of the modulus. Applications are given to simultaneous non-vanishing and lower bounds on higher moments of twisted L-functions.