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Arithmetic hypergeometric π-modules and exponential sums on reductive groups
Abstract
For a finite family of representations of a reductive group, we define a Laurent polynomial on the group. The exponential sum associated this Laurent polynomial is called a hypergeometric exponential sum. We introduce an arithmetic hypergeometric π-module to study the hypergeometric exponential sum. It is an overholonomic arithmetic π-module with a Frobenius structure so that the trace of the Frobenius at a rational point is the exponential sum. We prove that over the locus where the Laurent polynomial is nondegenerate, the arithmetic hypergeometric π-module defines an F-isocrystal overconvergent along the degenerate locus. As an application, we get an estimation of the hypergeometric exponential sum.
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BibTeX
@misc{fu2026arithmetic,
title = {{Arithmetic hypergeometric $\mathcal D$-modules and exponential sums on reductive groups}},
author = {Lei Fu and Xuanyou Li and Chenhan Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.00470},
eprint = {2608.00470},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.00470},
}
RIS
TY - UNPB
TI - Arithmetic hypergeometric π-modules and exponential sums on reductive groups
AU - Lei Fu
AU - Xuanyou Li
AU - Chenhan Liu
PY - 2026
DA - 2026/10/14
PB - arXiv
DO - 10.48550/arxiv.2608.00470
UR - https://arxiv.org/abs/2608.00470
AB - For a finite family of representations of a reductive group, we define a Laurent polynomial on the group. The exponential sum associated this Laurent polynomial is called a hypergeometric exponential sum. We introduce an arithmetic hypergeometric π-module to study the hypergeometric exponential sum. It is an overholonomic arithmetic π-module with a Frobenius structure so that the trace of the Frobenius at a rational point is the exponential sum. We prove that over the locus where the Laurent polynomial is nondegenerate, the arithmetic hypergeometric π-module defines an F-isocrystal overconvergent along the degenerate locus. As an application, we get an estimation of the hypergeometric exponential sum.
ER -