The Second Moment of Sums of Hecke Eigenvalues II

Fuente: arXiv
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Main Author: Carmichael, Ned
Format: Preprint
Published: 2025
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author Carmichael, Ned
author_facet Carmichael, Ned
contents Let $f$ be a holomorphic Hecke cusp form of weight $k$ for $\mathrm{SL}_2(\mathbb{Z})$, and let $(λ_f(n))_{n\geq 1}$ denote its sequence of normalised Hecke eigenvalues. We compute the first and second moments of the sums $S(x,f)=\sum_{x\leq n\leq 2x} λ_f(n)$, on average over forms $f$ of large weight $k$. In the range $k^2/(8π^2)\leq x\leq k^{12/5-ε}$, the size of the second moment lies between $x^{1/2-o(1)}$ and $x^{1/2}$. This is in sharp contrast to the regime $x\leq k^{2-o(1)}$, where the second moment was shown in preceding work (part I) to be of size $\asymp x$.
format Preprint
id arxiv_https___arxiv_org_abs_2502_03436
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Second Moment of Sums of Hecke Eigenvalues II
Carmichael, Ned
Number Theory
11F30 (Primary) 11N37, 11F11 (Secondary)
Let $f$ be a holomorphic Hecke cusp form of weight $k$ for $\mathrm{SL}_2(\mathbb{Z})$, and let $(λ_f(n))_{n\geq 1}$ denote its sequence of normalised Hecke eigenvalues. We compute the first and second moments of the sums $S(x,f)=\sum_{x\leq n\leq 2x} λ_f(n)$, on average over forms $f$ of large weight $k$. In the range $k^2/(8π^2)\leq x\leq k^{12/5-ε}$, the size of the second moment lies between $x^{1/2-o(1)}$ and $x^{1/2}$. This is in sharp contrast to the regime $x\leq k^{2-o(1)}$, where the second moment was shown in preceding work (part I) to be of size $\asymp x$.
title The Second Moment of Sums of Hecke Eigenvalues II
topic Number Theory
11F30 (Primary) 11N37, 11F11 (Secondary)
url https://arxiv.org/abs/2502.03436