A Bessel $\delta$-method and hybrid bounds for ${\mathrm{GL}}_2$

Yilan Fan, Qingfeng Sun

Let $g$ be a primitive holomorphic or Maass newform for ${\Gamma }_0(D)$. In this paper, by studying the Bessel integrals associated to $g$, we prove an asymptotic Bessel $\delta$-identity asso…