Rendiconti del Seminario Matematico della Università di Padova


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Volume 137, 2017, pp. 101–133
DOI: 10.4171/RSMUP/137-6

Published online: 2017-05-12

Weak local-global compatibility in the $p$-adic Langlands program for $U(2)$

Przemyslaw Chojecki[1] and Claus Sorensen[2]

(1) Oxford University, UK
(2) University of California, San Diego, USA

We study the completed cohomology $\widehat{H}^0$ of a definite unitary group $G$ in two variables associated with a CM-extension $\mathcal K/F$. When the prime $p$ splits, we prove that (under technical asumptions) the $p$-adic local Langlands correspondence for GL$_2(\mathbb Q_p)$ occurs in $\widehat{H}^0$. As an application, we obtain a result towards the Fontaine–Mazur conjecture over $\mathcal K$. If $x$ is a point on the eigenvariety such that $\rho_x$ is geometric (and satisfying additional hypotheses which we suppress), then $x$ must be a classical point. Thus, not only is $\rho_x$ modular, but the weight of $x$ defines an accessible refinement. This follows from a recent result of Colmez (which describes the locally analytic vectors in $p$-adic unitary principal series), knowing that $\rho_x$ admits a triangulation compatible with the weight.

Keywords: Galois representations, automorphic forms, $p$-adic Langlands program

Chojecki Przemyslaw, Sorensen Claus: Weak local-global compatibility in the $p$-adic Langlands program for $U(2)$. Rend. Sem. Mat. Univ. Padova 137 (2017), 101-133. doi: 10.4171/RSMUP/137-6