On discrete mean values of Dirichlet $L$-functions

Elma, Ertan

Czechoslovak Mathematical Journal, Tome 71 (2021) no. 4, pp. 1035-1048.

Résumé

Let $\chi $ be a nonprincipal Dirichlet character modulo a prime number $p\geqslant 3$ and let $\mathfrak a_\chi := \tfrac 12 (1-\chi (-1))$. Define the mean value $$ \mathcal {M}_{p}(-s,\chi ) :=\frac {2}{p-1} \sum \psi \pmod p \psi (-1)=-1 L(1,\psi )L(-s,\chi \bar {\psi }) \quad (\sigma :=\Re s>0). $$ We give an identity for $\mathcal {M}_{p}(-s,\chi )$ which, in particular, shows that $$ \mathcal {M}_{p}(-s,\chi )= L(1-s,\chi )+\mathfrak a_\chi 2p^s L(1,\chi )\zeta (-s) +o(1) \quad (p\rightarrow \infty ) $$ for fixed $0\sigma \frac {1}{2}$ and $|t:=\Im s|=o (p^{(1-2\sigma )/(3+2\sigma )})$.

Détail

DOI : 10.21136/CMJ.2021.0189-20

Classification : 11L40, 11M06
Keywords: Dirichlet $L$-function; mean value; Dirichlet character