Extreme values of the Riemann zeta function on the 1-line

Abstract

We prove that there are arbitrarily large values of $t$ such that $|\zeta (1+it)|\ge e^{\gamma }({\log }_{2}t+{\log }_{3}t)+\mathcal{O}(1)$. This essentially matches the prediction for the optimal lower bound in a conjecture of Granville and Soundararajan. Our proof uses a new variant of the "long resonator" method. While earlier implementations of this method crucially relied on a "sparsification" technique to control the mean-square of the resonator function, in the present paper we exploit certain self-similarity properties of a specially designed resonator function.

arXiv comment7 pages. Versions 2: several minor changes. The paper will appear in IMRN