Quotients of $L$-functions: degrees $n$ and $n-2$
Ravi Raghunathan
Abstract
If $L(s,π)$ and $L(s,ρ)$ are the Dirichlet series attached to cuspidal automorphic representations $π$ and $ρ$ of ${\rm GL}_n({\mathbb A}_{\mathbb Q})$ and ${\rm GL}_{n-2}({\mathbb A}_{\mathbb Q})$ respectively, we show that $F_2(s)=L(s,π)/L(s,ρ)$ has infinitely many poles. We also establish analogous results for Artin $L$-functions and other $L$-functions not yet proven to be automorphic. Using the classification theorems of \cite{Ragh20} and \cite{BaRa20}, we show that cuspidal $L$-functions of ${\rm GL}_3({\mathbb A}_{\mathbb Q})$ are primitive in ${\mathfrak G}$, a monoid that contains both the Selberg class ${\mathcal{S}}$ and $L(s,σ)$ for all unitary cuspidal automorphic representations $σ$ of ${\rm GL}_n({\mathbb A}_{\mathbb Q})$.
