The regularity of difference divisors

Abstract

For a prime number \(p>2\) and a finite extension \(F/\mathbb {Q}_p\), we explain the construction of the difference divisors on the unitary Rapoport–Zink spaces of hyperspecial level over \(\mathcal {O}_{\breve{F}}\), and the GSpin Rapoport–Zink spaces of hyperspecial level over \(\breve{\mathbb {Z}}_{p}\) associated to a minuscule cocharacter \(\mu \) and a basic element b. We prove the regularity of the difference divisors, find the formally smooth locus of both the special cycles and the difference divisors, by a purely deformation-theoretic approach.