English

Galois representations over convergent de Rham period ring

Number Theory 2026-05-12 v2

Abstract

Let BdR+,BdR+\mathbf{B}_{\mathrm{dR}}^{+, \dagger} \subset \mathbf{B}_{\mathrm{dR}}^{+} be the ``convergent" de Rham period ring which is the (un-completed) stalk at the de Rham point of the Fargues--Fontaine curve. We develop a Tate--Sen formalism to relate Galois representations over BdR+,\mathbf{B}_{\mathrm{dR}}^{+, \dagger} to regular connections over convergent functions. As a consequence, when the Sen weights (of the mod tt reduction) satisfy a pp-adic non-Liouville condition, Galois cohomology of a BdR+,\mathbf{B}_{\mathrm{dR}}^{+, \dagger}-representation compares to that of its BdR+\mathbf{B}_{\mathrm{dR}}^{+}-base change, and hence is finite. In addition, restricted to objects whose Sen weights are algebraic numbers, the categories of BdR+,\mathbf{B}_{\mathrm{dR}}^{+, \dagger}-representations and BdR+\mathbf{B}_{\mathrm{dR}}^{+}-representations are equivalent.

Keywords

Cite

@article{arxiv.2604.21605,
  title  = {Galois representations over convergent de Rham period ring},
  author = {Hui Gao and Yupeng Wang},
  journal= {arXiv preprint arXiv:2604.21605},
  year   = {2026}
}

Comments

v2: very minor revisions/simplifications. 40 pages. Comments welcome!