Big principal series, p-adic families and L-invariants

TL;DR

This paper extends the computation of automorphic $ ext{L}$-invariants to higher rank groups using $p$-adic families, proving invariance properties and connecting them to Galois representations, with applications to Hilbert and Bianchi modular forms.

Contribution

It introduces a new method to compute automorphic $ ext{L}$-invariants via derivatives in $p$-adic families, generalizing previous results and proving invariance properties.

Findings

Automorphic $ ext{L}$-invariants are independent of sign characters.

They are invariant under Jacquet-Langlands transfer.

They equal Fontaine-Mazur $ ext{L}$-invariants of Galois representations.

Abstract

In earlier work, the first named author generalized the construction of Darmon-style $\mathcal{L}$-invariants to cuspidal automorphic representations of semisimple groups of higher rank, which are cohomological with respect to the trivial coefficient system and Steinberg at a fixed prime. In this paper, assuming that the Archimedean component of the group has discrete series we show that these automorphic $\mathcal{L}$-invariants can be computed in terms of derivatives of Hecke-eigenvalues in $p$-adic families. Our proof is novel even in the case of modular forms, which was established by Bertolini, Darmon, and Iovita. The main new technical ingredient is the Koszul resolution of locally analytic principal series representations by Kohlhaase and Schraen. As an application of our results we settle a conjecture of Spie{\ss}: we show that automorphic $\mathcal{L}$-invariants of Hilbert modular forms of parallel weight $2$ are independent of the sign character used to define them. Moreover, we show that they are invariant under Jacquet-Langlands transfer and, in fact, equal to the Fontaine-Mazur $\mathcal{L}$-invariant of the associated Galois representation. Under mild assumptions, we also prove the equality of automorphic and Fontaine-Mazur $\mathcal{L}$-invariants for representations of definite unitary groups of arbitrary rank. Finally, we study the case of Bianchi modular forms to show how our methods, given precise results on eigenvarieties, can also work in the absence of discrete series representations.