English

Distinguishing Galois representations by their normalized traces

Number Theory 2016-10-03 v1

Abstract

Suppose ρ1 \rho_1 and ρ2 \rho_2 are two pure Galois representations of the absolute Galois group of a number field KK of weights k1 k_1 and k2 k_2 respectively, having equal normalized Frobenius traces Tr(ρ1(σv))/Nvk1/2 Tr(\rho_1(\sigma_v)) /Nv^{k_1/2} and Tr(ρ2(σv))/Nvk2/2 Tr(\rho_2(\sigma_v)) /Nv^{k_2/2} at a set of primes v v of KK with positive upper density. Assume further that the algebraic monodromy group of ρ1\rho_1 is connected and the repesentation is absolutely irreducible. We prove that ρ1 \rho_1 and ρ2 \rho_2 are twists of each other by power of a Tate twist times a character of finite order. We apply this to modular forms and deduce a result proved by Murty and Pujahari.

Keywords

Cite

@article{arxiv.1609.09724,
  title  = {Distinguishing Galois representations by their normalized traces},
  author = {Vijay M. Patankar and C. S. Rajan},
  journal= {arXiv preprint arXiv:1609.09724},
  year   = {2016}
}
R2 v1 2026-06-22T16:06:38.742Z