Exceptional characters and nonvanishing of Dirichlet $L$-functions

H. M. Bui, Kyle Pratt, Alexandru Zaharescu

Let $\psi$ be a real primitive character modulo $D$. If the $L$-function $L(s,\psi )$ has a real zero close to $s=1$, known as a Landau-Siegel zero, then we say the character $\psi$ is excep…