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arXiv · 2608.25812

The second moment of twisted modular $L$-functions and Dirichlet $L$-functions at the central point

Zhengye Chen·Yongxiao Lin
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Abstract

We prove an asymptotic formula with a power-saving error term for the second moment $$ \sum_{q \in \mathcal{Q}} \; \; \sideset{}{^\flat}\sum_{\chi \bmod q} \left| L\big( \tfrac{1}{2} , \chi \big) L\big(\tfrac{1}{2},f\otimes \chi)\right|^2 $$ of the twisted ${\rm GL}(2)$ {$L$}-function and the Dirichlet {$L$}-function at the central point under the assumption of Selberg's eigenvalue conjecture. Here $f$ is a fixed Hecke holomorphic cusp form for $\mathrm{SL}(2,\mathbb{Z})$ and the sum over $\chi$ runs over all primitive even Dirichlet characters modulo $q$, and $$\mathcal{Q}=\left\{q=q_1 q_2\asymp Q: q_1 \leq Q_1, q_2 \leq Q_2,\ Q_2\asymp Q^{\delta_1},(q,6)=1,(q_1,q_2)=1 \right\}$$ with $0<\delta_1<0.0004$.

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Zhengye Chen, Yongxiao Lin. 2026-08-26. The second moment of twisted modular $L$-functions and Dirichlet $L$-functions at the central point. https://arxiv.org/abs/2608.25812

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