16:00
Propagating Langlands functoriality on eigenvarieties
Abstract
A test case for the Langlands functoriality principle is the tensor product lifting of automorphic representations of $\mathrm{GL}(m) \times \mathrm{GL}(n)$ to automorphic representations of $\mathrm{GL}(mn)$. This has been established in several key instances: for $m=n=2$ by Ramakrishnan (2000), for $m=2$ and $n=3$ by Kim-Shahidi (2002), and more recently for $m=2$ and arbitrary $n$ over $\mathbb{Q}$ by Arias-de-Reyna-Dieulefait-Pérez (2025) under certain assumptions, including that the $\mathrm{GL}(2)$ factor has level 1. I will discuss some new results in the case of $\mathrm{GL}(2) \times \mathrm{GL}(n)$, as well as ideas for how to go further, when $m>2$, using a p-adic propagation technique introduced by Newton-Thorne (2021).