English

Ekedahl-Oort strata in the $\mathsf{GU}(q-2,2)$ Shimura variety

Number Theory 2025-10-03 v3 Algebraic Geometry

Abstract

This paper concerns the characteristic-pp fibers of GU(q2,2)\mathsf{GU}(q-2,2) Shimura varieties, which classify abelian varieties with additional structure. These Shimura varieties admit two stratifications of interest: the Ekedahl-Oort stratification, based on the isomorphism class of the pp-torsion subgroup scheme, and the Newton stratification, based on the isogeny class of the pp-divisible group. In this paper, we present several novel techniques that give a better understanding of the Ekedahl-Oort stratification and of the interaction between the two stratifications for a general signature (q2,2)(q-2,2).

Keywords

Cite

@article{arxiv.2405.04464,
  title  = {Ekedahl-Oort strata in the $\mathsf{GU}(q-2,2)$ Shimura variety},
  author = {Emerald Andrews and Deewang Bhamidipati and Maria Fox and Heidi Goodson and Steven R. Groen and Sandra Nair},
  journal= {arXiv preprint arXiv:2405.04464},
  year   = {2025}
}

Comments

35 pages. Title updated. Section 3 updated with general results. Section 6 split off into arxiv:2510.01090