$R=T$ theorems for weight one modular forms

Tobias Berger; Krzysztof Klosin

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arXiv · 2203.09434

$R=T$ theorems for weight one modular forms

Tobias Berger·Krzysztof Klosin

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Abstract

We prove modularity of certain residually reducible ordinary 2-dimensional $p$-adic Galois representations with determinant a finite order odd character $\chi$. For certain non-quadratic $\chi$ we prove an $R=T$ result for $T$ the weight 1 specialisation of the Hida Hecke algebra acting on non-classical weight 1 forms, under the assumption that no two Hida families congruent to an Eisenstein series cross in weight 1. For quadratic $\chi$ we prove that the quotient of $R$ corresponding to deformations split at $p$ is isomorphic to the Hecke algebra acting on classical CM weight 1 modular forms.

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Tobias Berger, Krzysztof Klosin. 2022-03-17. $R=T$ theorems for weight one modular forms. https://arxiv.org/abs/2203.09434

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