Bounds for moments of quadratic character sums and theta functions

Fuente: arXiv
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Autores principales: Munsch, Marc, Toma, Yuichiro
Formato: Preprint
Publicado: 2025
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author Munsch, Marc
Toma, Yuichiro
author_facet Munsch, Marc
Toma, Yuichiro
contents In this paper, we investigate the size of moments of quadratic character sums averaged over the family of fundamental discriminants. We obtain an asymptotic formula for all integer moments in a restricted range of parameters using a multivariate tauberian theorem. As a consequence, we prove unconditional lower bounds for all even integer moments of quadratic character sums in a wide range of parameters. Moreover, assuming the Generalised Riemann Hypothesis (GRH), we prove a sharp upper bound on moments of character sums of arbitrary length. In a similar fashion, we obtain unconditional lower bounds on moments of quadratic theta functions and matching conditional upper bounds under GRH. In the case of the second moment of theta functions, we prove an optimal upper bound unconditionally improving the previous results of Louboutin and the first named author.
format Preprint
id arxiv_https___arxiv_org_abs_2503_05269
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Bounds for moments of quadratic character sums and theta functions
Munsch, Marc
Toma, Yuichiro
Number Theory
11L40 (Primary), 11M06 (Primary), 11N37 (Primary)
In this paper, we investigate the size of moments of quadratic character sums averaged over the family of fundamental discriminants. We obtain an asymptotic formula for all integer moments in a restricted range of parameters using a multivariate tauberian theorem. As a consequence, we prove unconditional lower bounds for all even integer moments of quadratic character sums in a wide range of parameters. Moreover, assuming the Generalised Riemann Hypothesis (GRH), we prove a sharp upper bound on moments of character sums of arbitrary length. In a similar fashion, we obtain unconditional lower bounds on moments of quadratic theta functions and matching conditional upper bounds under GRH. In the case of the second moment of theta functions, we prove an optimal upper bound unconditionally improving the previous results of Louboutin and the first named author.
title Bounds for moments of quadratic character sums and theta functions
topic Number Theory
11L40 (Primary), 11M06 (Primary), 11N37 (Primary)
url https://arxiv.org/abs/2503.05269