On divisor bounded multiplicative functions in short intervals

Fuente: arXiv
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Main Author: Sun, Yu-Chen
Format: Preprint
Published: 2024
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author Sun, Yu-Chen
author_facet Sun, Yu-Chen
contents Let $d_k(n) = \sum_{n_1 \cdots n_k = n}1$ be the $k$-fold divisor function. We call a function $f:\mathbb{N} \to \mathbb{C}$ a $d_k$-bounded multiplicative function, if $f$ is multiplicative and $|f(n)| \leq d_k(n)$ for every $n \in \mathbb{N}$. In this paper we improve Mangerel's results which extend the Matomäki-Radziwi{łł} theorem to divisor bounded multiplicative functions. In particular, we prove that for sufficiently large $X \geq 2$, any $ε>0$ and $h \geq (\log X)^{k \log k - k + 1 + ε}$ , we have $$ \frac{1}{h}\sum_{x<n\leq x+h}d_k(n)-\frac{1}{x}\sum_{x<n\leq 2x}d_{k}(n) = o(\log^{k-1} x) $$ for almost all $x \in [X,2X]$. We also demonstrate that the exponent $k \log k-k+1$ is optimal.
format Preprint
id arxiv_https___arxiv_org_abs_2401_08432
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On divisor bounded multiplicative functions in short intervals
Sun, Yu-Chen
Number Theory
Let $d_k(n) = \sum_{n_1 \cdots n_k = n}1$ be the $k$-fold divisor function. We call a function $f:\mathbb{N} \to \mathbb{C}$ a $d_k$-bounded multiplicative function, if $f$ is multiplicative and $|f(n)| \leq d_k(n)$ for every $n \in \mathbb{N}$. In this paper we improve Mangerel's results which extend the Matomäki-Radziwi{łł} theorem to divisor bounded multiplicative functions. In particular, we prove that for sufficiently large $X \geq 2$, any $ε>0$ and $h \geq (\log X)^{k \log k - k + 1 + ε}$ , we have $$ \frac{1}{h}\sum_{x<n\leq x+h}d_k(n)-\frac{1}{x}\sum_{x<n\leq 2x}d_{k}(n) = o(\log^{k-1} x) $$ for almost all $x \in [X,2X]$. We also demonstrate that the exponent $k \log k-k+1$ is optimal.
title On divisor bounded multiplicative functions in short intervals
topic Number Theory
url https://arxiv.org/abs/2401.08432