The basic locus of ramified unitary Rapoport-Zink space at maximal vertex level (2502.06218v1)

Abstract: We construct the Bruhat-Tits stratification of the ramified unitary Rapoport-Zink space, with the level being the stabilizer of a vertex lattice. We develop the local model theory for Bruhat-Tits strata, proving their normality and Cohen-Macaulayness, and provide precise dimension formulas. Additionally, we establish an explicit isomorphism between Bruhat-Tits strata and Deligne-Lusztig varieties, revealing new phenomena beyond the previously studied Coxeter-type cases.