English

The Breuil--M\'{e}zard conjecture when $l \neq p$

Number Theory 2018-05-23 v2

Abstract

Let ll and pp be primes, let F/QpF/\mathbb{Q}_p be a finite extension with absolute Galois group GFG_F, let F\mathbb{F} be a finite field of characteristic ll, and let ρˉ:GFGLn(F)\bar{\rho} : G_F \rightarrow GL_n(\mathbb{F}) be a continuous representation. Let R(ρˉ)R^\square(\bar{\rho}) be the universal framed deformation ring for ρˉ\bar{\rho}. If l=pl = p, then the Breuil--M\'{e}zard conjecture (as formulated by Emerton and Gee) relates the mod ll reduction of certain cycles in R(ρˉ)R^\square(\bar{\rho}) to the mod ll reduction of certain representations of GLn(OF)GL_n(\mathcal{O}_F). We state an analogue of the Breuil--M\'{e}zard conjecture when lpl \neq p, and prove it whenever l>2l > 2 using automorphy lifting theorems. We give a local proof when ll is "quasi-banal" for FF and ρˉ\bar{\rho} is tamely ramified. We also analyse the reduction modulo ll of the types σ(τ)\sigma(\tau) defined by Schneider and Zink.

Keywords

Cite

@article{arxiv.1608.01784,
  title  = {The Breuil--M\'{e}zard conjecture when $l \neq p$},
  author = {Jack Shotton},
  journal= {arXiv preprint arXiv:1608.01784},
  year   = {2018}
}

Comments

56 pages. To appear in Duke Math. Journal

R2 v1 2026-06-22T15:13:03.400Z