The shifted convolution problem in function fields

Fuente: arXiv
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Autori principali: Florea, Alexandra, Lalín, Matilde, Malik, Amita, Sahay, Anurag
Natura: Preprint
Pubblicazione: 2025
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author Florea, Alexandra
Lalín, Matilde
Malik, Amita
Sahay, Anurag
author_facet Florea, Alexandra
Lalín, Matilde
Malik, Amita
Sahay, Anurag
contents We study the shifted convolution problem for the divisor function in function fields in the large degree limit, that is, the average value of $d(f) d(f+h)$ where $f$ runs over monic polynomials in $\mathbb{F}_q[T]$ of a given degree, and $h$ is a given monic polynomial. We prove an asymptotic formula in the range $\operatorname{deg}(h) < (2-ε)\operatorname{deg}(f)$. We also consider mixed correlations and self-correlations of $r_χ= 1 \star χ$, the convolution of $1$ with a Dirichlet character mod $\ell$, where $\ell$ is a monic irreducible polynomial, proving asymptotic formulae in various ranges. This includes the case of quadratic characters, which yields results about correlations of norm-counting functions of quadratic extensions of $\mathbb{F}_q[T]$. A novel feature of our work is a Voronoi summation formula (equivalently, a functional equation for the Estermann function) in $\mathbb{F}_q[T]$ which was not previously available.
format Preprint
id arxiv_https___arxiv_org_abs_2502_16067
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The shifted convolution problem in function fields
Florea, Alexandra
Lalín, Matilde
Malik, Amita
Sahay, Anurag
Number Theory
11N37, 11R58, 11R59
We study the shifted convolution problem for the divisor function in function fields in the large degree limit, that is, the average value of $d(f) d(f+h)$ where $f$ runs over monic polynomials in $\mathbb{F}_q[T]$ of a given degree, and $h$ is a given monic polynomial. We prove an asymptotic formula in the range $\operatorname{deg}(h) < (2-ε)\operatorname{deg}(f)$. We also consider mixed correlations and self-correlations of $r_χ= 1 \star χ$, the convolution of $1$ with a Dirichlet character mod $\ell$, where $\ell$ is a monic irreducible polynomial, proving asymptotic formulae in various ranges. This includes the case of quadratic characters, which yields results about correlations of norm-counting functions of quadratic extensions of $\mathbb{F}_q[T]$. A novel feature of our work is a Voronoi summation formula (equivalently, a functional equation for the Estermann function) in $\mathbb{F}_q[T]$ which was not previously available.
title The shifted convolution problem in function fields
topic Number Theory
11N37, 11R58, 11R59
url https://arxiv.org/abs/2502.16067