A note on order estimates of the $q$-analogue of the Riemann zeta function
Hideki Murahara, Tomokazu Onozuka
TL;DR
The paper derives growth estimates on vertical lines for the $q$-analogue of the Riemann zeta function, $\zeta_q(s,t)$, and its specialization $\zeta_q(s)$, by decomposing a key representation into a finite part and a controllable tail. Using Stirling-type bounds on binomial coefficients and an optimal truncation parameter $N$ that scales with the imaginary height $|v|$, it establishes explicit bounds that depend on the sign of $\Re(t)$. The results show polynomial growth when $\Re(t)\ge0$ and exponential decay when $\Re(t)<0$, with a corollary giving analogous bounds for $\zeta_q(s)$ and a definition of $\mu_q(\sigma)$ capturing the vertical-growth rate. The work highlights a gap with the classical Lindelöf hypothesis due to fixed $q$ and anticipates convergence to the classical bounds as $q\to1$, contributing toward understanding $q$-deformations of zeta-type objects.
Abstract
At the first step of studying order estimates for the $q$-analogue of the Riemann zeta function, we estimate bounds for it on vertical lines for a fixed parameter $q$.
