English

Bruhat-Tits buildings and $p$-adic period domains

Number Theory 2025-02-20 v1 Algebraic Geometry

Abstract

Let GG be a connected reductive group over a pp-adic local field FF. R\'emy-Thuillier-Werner constructed embeddings of the (reduced) Bruhat-Tits building B(G,F)\mathcal{B}(G,F) into the Berkovich spaces associated to suitable flag varieties of GG, generalizing the work of Berkovich in split case. They defined compactifications of B(G,F)\mathcal{B}(G,F) by taking closure inside these Berkovich flag varieties. We show that, in the setting of a basic local Shimura datum, the R\'emy-Thuillier-Werner embedding factors through the associated pp-adic Hodge-Tate period domain. Moreover, we compare the boundaries of the Berkovich compactification of B(G,F)\mathcal{B}(G,F) with non basic Newton strata. In the case of GLn\mathrm{GL}_n and the cocharacter μ=(1d,0nd)\mu=(1^d, 0^{n-d}) for an integer dd which is coprime to nn, we further construct a continuous retraction map from the pp-adic period domain to the building. This reveals new information on these pp-adic period domains, which share many similarities with the Drinfeld spaces.

Keywords

Cite

@article{arxiv.2502.13468,
  title  = {Bruhat-Tits buildings and $p$-adic period domains},
  author = {Xu Shen and Ruishen Zhao},
  journal= {arXiv preprint arXiv:2502.13468},
  year   = {2025}
}

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45 pages