On $p$-adic $L$-functions for $\operatorname{GL}(2)\times\operatorname{GL}(3)$ via pullbacks of Saito--Kurokawa lifts

Abstract: We build a one-variable $p$-adic $L$-function attached to two Hida families of ordinary $p$-stabilised newforms $\mathbf{f}$, $\mathbf{g}$, interpolating the algebraic part of the central values of the complex $L$-series $L(f \otimes \textrm{Ad}(g), s)$ when $f$ and $g$ range over the classical specialisations of $\mathbf{f}$, $\mathbf{g}$ on a suitable line of the weight space. The construction rests on two major results: an explicit formula for the relevant complex central $L$-values, and the existence of non-trivial $\Lambda$-adic Shintani liftings and Saito--Kurokawa liftings studied in a previous work by the authors. We also illustrate that, under an appropriate sign assumption, this $p$-adic $L$-function arises as a factor of a triple product $p$-adic $L$-function attached to $\mathbf{f}$, $\mathbf{g}$, and $\mathbf{g}$.