Sato-Tate Distribution of $p$-adic hypergeometric functions

TL;DR

This paper studies the distribution of $p$-adic hypergeometric functions over large finite fields, showing they follow semicircular distributions, and relates these to traces of Hecke operators on certain modular forms.

Contribution

It extends the understanding of hypergeometric function distributions into the $p$-adic setting and connects them with modular form trace formulas.

Findings

$p$-adic hypergeometric functions have semicircular limiting distributions.

Traces of $p$th Hecke operators are expressed in terms of $p$-adic hypergeometric functions.

Results generalize previous Gaussian hypergeometric distribution findings.

Abstract

Recently Ono, Saad and the second author \cite{KHN} initiated a study of value distribution of certain families of Gaussian hypergeometric functions over large finite fields. They investigated two families of Gaussian hypergeometric functions and showed that they satisfy semicircular and Batman distributions. Motivated by their results we aim to study distributions of certain families of hypergeometric functions in the $p$-adic setting over large finite fields. In particular, we consider two and six parameters families of hypergeometric functions in the $p$-adic setting and obtain that their limiting distributions are semicircular over large finite fields. In the process of doing this we also express the traces of $p$th Hecke operators acting on the spaces of cusp forms of even weight $k\geq4$ and levels 4 and 8 in terms of $p$-adic hypergeometric function which is of independent interest. These results can be viewed as $p$-adic analogous of some trace formulas of \cite{ah, ah-ono, fop}.