Large values of the Hurwitz zeta function with rational parameter

Abstract: In this paper, we establish lower bounds for large values of the Hurwitz zeta function with rational parameter when the real part $σ\in [1/2,1]$. These results improve the earlier results of Ramachandra and Sankaranarayanan in 1989. On the critical line, our result recovers the corresponding lower bound of de la Bretèche and Tenenbaum (2019) for the Riemann zeta function, while for $1/2< σ\leq 1$, our lower bounds attain the same order as the corresponding lower bounds for large values of the Riemann zeta function. Our proofs are based on the resonance method.