English

Crystalline Chebotar\"ev density theorems

Number Theory 2025-11-21 v3

Abstract

Using the Tannakian formalism, we formulate conjectural analogs of Chebotar\"ev's Density Theorem for FF-isocrystals over a smooth geometrically irreducible variety defined over a finite field. We prove these analogs for several large classes, including (a) constant FF-isocrystals, (b) direct sums of isoclinic convergent FF-isocrystals, (c) semi-simple overconvergent FF-isocrystals, and (d) semi-simple convergent FF-isocrystals which have an overconvergent extension. Case (a) is a generalization of the Mordell-Lang Conjecture for tori and enters in the proofs of (b) and (c). For (b) we use the classical Chebotar\"ev Density Theorem, and point counting techniques in pp-adic Lie groups building on a result of Oesterl\'e. For (c) we give two proofs. One of them uses deep input on the Langlands correspondence by Abe and Lafforgue, and the theory of Frobenius weights of Kedlaya, Abe and Caro. Building on this we formulate and prove the pp-adic analog of Deligne's Equidistribution Theorem. Then (c) follows by applying real algebraic geometry to maximal compact subgroups in complex algebraic groups, measure theory, and a convergence result on complex hypersurfaces. For (d) we develop the theory of maximal quasi-tori (generalizing maximal tori in non-connected linear algebraic groups) and use D'Addezio's result on Crew's parabolicity conjecture to reduce to (b). These arguments also yield a second proof of (c). Besides of the deep inputs mentioned above and some Tannakian arguments, our main technique is the theory of linear algebraic groups. We include a comparison with the recent article of Cadoret and Tamagawa on the same topic.

Keywords

Cite

@article{arxiv.1811.07084,
  title  = {Crystalline Chebotar\"ev density theorems},
  author = {Urs Hartl and Ambrus Pal},
  journal= {arXiv preprint arXiv:1811.07084},
  year   = {2025}
}

Comments

v1: 72 pages, v2: 81 pages, Chapter 12 and Appendix B added, Proof of the overconvergent case corrected, various other small changes, v3: final version, 58 pages, major reorganization

R2 v1 2026-06-23T05:18:52.617Z