English

Potentially diagonalisable lifts with controlled Hodge--Tate weights

Number Theory 2019-04-30 v3

Abstract

Motivated by the weight part of Serre's conjecture we consider the following question. Let K/QpK/\mathbb{Q}_p be a finite extension and suppose ρ ⁣:GKGLn(Fp)\overline{\rho} \colon G_K \rightarrow \operatorname{GL}_n(\overline{\mathbb{F}}_p) admits a crystalline lift with Hodge--Tate weights contained in the range [0,p][0,p]. Does ρ\overline{\rho} admits a potentially diagonalisable crystalline lift of the same Hodge--Tate weights? We answer this question in the affirmative when K=QpK = \mathbb{Q}_p and n5n \leq 5, and ρ\overline{\rho} satisfies a mild `cyclotomic-free' condition. We also prove partial results when K/QpK/\mathbb{Q}_p is unramified and nn is arbitrary.

Keywords

Cite

@article{arxiv.1812.02042,
  title  = {Potentially diagonalisable lifts with controlled Hodge--Tate weights},
  author = {Robin Bartlett},
  journal= {arXiv preprint arXiv:1812.02042},
  year   = {2019}
}