On a level analog of Selberg's result on $S(t)$
Qingfeng Sun, Hui Wang, Yanxue Yu
TL;DR
This work establishes an unconditional level-aspect analogue of Selberg's results for S(t) in the GL2 setting of holomorphic weight-2 cusp forms at prime level q. It develops a precise truncated Dirichlet-series approximation for S(t,f) and leverages a weighted zero-density estimate to handle the family of L-functions, enabling exact moment asymptotics. The authors show that the even moments of S(t,f) scale like (log log q)^{n/2} with explicit constants and that odd moments vanish, leading to a weighted central limit theorem. Consequently, the distribution of S(t,f) normalized by √log log q converges to a Gaussian with mean 0 and variance 1/(2π^2) under the harmonic weight measure, revealing a level-aspect probabilistic behavior analogous to Selberg's classical results.
Abstract
Let $S(t,f)=π^{-1}\arg L(1/2+it, f)$, where $f$ is a holomorphic Hecke cusp form of weight $2$ and prime level $q$. In this paper, we establish an unconditional asymptotic formula for the moments of $S(t,f)$, providing a level aspect analogue of Selberg's classical work on $S(t)$. As a consequence, we derive a weighted central limit theorem for the distribution of $S(t,f)$ normalized by $\sqrt{\log\log q}$. To this end, we develop a precise approximation for $S(t,f)$ via a truncated Dirichlet series and employ a weighted zero-density estimate for the corresponding family of $L$-functions.
