English

$R=T$ theorems for weight one modular forms

Number Theory 2022-03-18 v1

Abstract

We prove modularity of certain residually reducible ordinary 2-dimensional pp-adic Galois representations with determinant a finite order odd character χ\chi. For certain non-quadratic χ\chi we prove an R=TR=T result for TT 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 χ\chi we prove that the quotient of RR corresponding to deformations split at pp is isomorphic to the Hecke algebra acting on classical CM weight 1 modular forms.

Keywords

Cite

@article{arxiv.2203.09434,
  title  = {$R=T$ theorems for weight one modular forms},
  author = {Tobias Berger and Krzysztof Klosin},
  journal= {arXiv preprint arXiv:2203.09434},
  year   = {2022}
}

Comments

32 pages

R2 v1 2026-06-24T10:17:21.211Z