English

Comparing Hecke eigenvalues for pairs of automorphic representations for GL(2)

Number Theory 2026-04-16 v3

Abstract

We consider a variant of the strong multiplicity one theorem. Let π1\pi_{1} and π2\pi_{2} be two unitary cuspidal automorphic representations for GL(2)\mathrm{GL(2)} that are not twist-equivalent. We find a lower bound for the lower Dirichlet density of the set of places for which av(π1)>av(π2)\left\lvert a_{v}(\pi_{1}) \right\rvert > \left\lvert a_{v}(\pi_{2}) \right\rvert, where av(πi)a_{v}(\pi_{i}) is the trace of Langlands conjugacy class of πi\pi_{i} at vv. One consequence of this result is an improvement on the existing bound on the lower Dirichlet density of the set of places for which av(π1)av(π2)\left\lvert a_{v}(\pi_{1})\right\rvert \neq \left\lvert a_{v}(\pi_{2}) \right\rvert.

Keywords

Cite

@article{arxiv.2408.01643,
  title  = {Comparing Hecke eigenvalues for pairs of automorphic representations for GL(2)},
  author = {Kin Ming Tsang},
  journal= {arXiv preprint arXiv:2408.01643},
  year   = {2026}
}

Comments

Revised version

R2 v1 2026-06-28T18:02:52.161Z