Explicit extreme values of the argument of the Riemann zeta-function
Shōta Inoue, Hirotaka Kobayashi, Yuichiro Toma
TL;DR
This work studies explicit extreme values of the argument $S(t)$ of the Riemann zeta-function on the critical line, focusing on short-interval differences $S(t+h)-S(t)$ and their connection to gaps between zeta zeros. By deploying the resonance method with Dirichlet-polynomial resonators, the authors derive RH-conditional lower bounds for these short-interval extrema and translate them into explicit bounds for the normalized $r$-gaps $\lambda_r$ and $\mu_r$, improving constants toward the conjectured extremal values. They obtain, for large $r$, $\lambda_r \ge 1 + \sqrt{2}/\sqrt{r} - C_1 (\log r)^{3/2}/r$ and $\mu_r \le 1 - \sqrt{2}/\sqrt{r} + C_2 (\log r)^{3/2}/r$, under RH, thereby strengthening previous results. The paper also analyzes limitations of the Montgomery–Odlyzko approach, proving barriers such as $\lambda_1 \ge 3.022$ and $\mu_1 \le 0.508$, and discusses the optimality of the $\sqrt{2}$ constant within that framework.
Abstract
We investigate explicit extreme values of the argument of the Riemann zeta-function in short intervals. As an application, we improve the result of Conrey and Turnage-Butterbaugh concerning $r$-gaps between zeros of the Riemann zeta-function.
