English

A note on log-type GCD sums and derivatives of the Riemann zeta function

Number Theory 2023-07-06 v3

Abstract

In [Yan22a], we defined so-called ``log-type" GCD sums and proved the lower bounds Γ1()(N)(loglogN)2+2\Gamma^{(\ell)}_1(N) \gg_{\ell} \left(\log\log N\right)^{2+2\ell}. We will establish the upper bounds Γ1()(N)(loglogN)2+2\Gamma^{(\ell)}_1(N)\ll_{\ell} \left(\log \log N\right)^{2+2\ell} in this note, which generalizes G\'{a}l's theorem on GCD sums (corresponding to the case =0\ell = 0). This result will be proved by two different methods. The first method is unconditional. We establish sharp upper bounds for spectral norms along α\alpha-lines when α\alpha tends to 11 with certain fast rates. As a corollary, we obtain upper bounds for log-type GCD sums. The second method is conditional. We prove that lower bounds for log-type GCD sums Γ1()(N)\Gamma^{(\ell)}_1(N) can produce lower bounds for large values of derivatives of the Riemann zeta function on the 1-line. So from conditional upper bound for ζ()(1+it)\left| \zeta^{(\ell)}\left(1+ i t\right)\right|, we obtain upper bounds for log-type GCD sums.

Keywords

Cite

@article{arxiv.2201.12968,
  title  = {A note on log-type GCD sums and derivatives of the Riemann zeta function},
  author = {Daodao Yang},
  journal= {arXiv preprint arXiv:2201.12968},
  year   = {2023}
}

Comments

3rd Version: 22 pages, new results (Theorem 1.3, 1.5) added. Corollary 2 improved. Remark 1.2, 1.4, 1.5 added