English

A Chebotarev Density Theorem over Local Fields

Number Theory 2025-07-08 v5 Algebraic Geometry

Abstract

We compute the pp-adic densities of points with a given splitting type along a (generically) finite map, analogous to the classical Chebotarev theorem over number fields and function fields. Under some mild hypotheses, we prove that these densities satisfy a functional equation in the size of the residue field. This functional equation is a direct reflection of Poincar\'e duality in \'etale cohomology. As a consequence, we prove a conjecture of Bhargava, Cremona, Fisher, and Gajovi\'c on factorization densities of p-adic polynomials. The key tool is the notion of admissible pairs associated to a group, which we use as an invariant of the inertia and decomposition action of a local field on the fibers of the finite map. We compute the splitting densities by M\"obius inverting certain p-adic integrals along the poset of admissible pairs. The conjecture on factorization densities follows immediately for tamely ramified primes from our general results. We reduce the complete conjecture (including the wild primes) to the existence of an explicit "Tate-type" resolution of the "resultant locus" over the integers and complete the proof of the conjecture by constructing this resolution.

Keywords

Cite

@article{arxiv.2212.00294,
  title  = {A Chebotarev Density Theorem over Local Fields},
  author = {Asvin G and Yifan Wei and John Yin},
  journal= {arXiv preprint arXiv:2212.00294},
  year   = {2025}
}

Comments

The final version, proving the complete conjecture on factorization densities including the wild case

R2 v1 2026-06-28T07:19:04.416Z