Eisenstein series modulo $p^2$

Fuente: arXiv
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Main Authors: Ahlgren, Scott, Hanson, Michael, Raum, Martin, Richter, Olav K.
Format: Preprint
Published: 2025
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author Ahlgren, Scott
Hanson, Michael
Raum, Martin
Richter, Olav K.
author_facet Ahlgren, Scott
Hanson, Michael
Raum, Martin
Richter, Olav K.
contents We study congruences for Eisenstein series on $\mathrm{SL}_2(\mathbb{Z})$ modulo $p^2$, where $p \geq 5$ is prime. It is classically known that all Eisenstein series of weight at least $4$ are determined modulo $p^2$ by those of weight at most $p^2-p+2$. We prove that up to powers of $E_{p-1}$, each such Eisenstein series is in fact determined modulo $p^2$ by a modular form of weight at most $2p-4$. We also determine $E_2$ modulo $p^2$ in terms of a modular form of weight $p+1$.
format Preprint
id arxiv_https___arxiv_org_abs_2502_16917
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Eisenstein series modulo $p^2$
Ahlgren, Scott
Hanson, Michael
Raum, Martin
Richter, Olav K.
Number Theory
We study congruences for Eisenstein series on $\mathrm{SL}_2(\mathbb{Z})$ modulo $p^2$, where $p \geq 5$ is prime. It is classically known that all Eisenstein series of weight at least $4$ are determined modulo $p^2$ by those of weight at most $p^2-p+2$. We prove that up to powers of $E_{p-1}$, each such Eisenstein series is in fact determined modulo $p^2$ by a modular form of weight at most $2p-4$. We also determine $E_2$ modulo $p^2$ in terms of a modular form of weight $p+1$.
title Eisenstein series modulo $p^2$
topic Number Theory
url https://arxiv.org/abs/2502.16917