Special endomorphisms of QM abelian surfaces

Abstract

In this paper we generalize a theorem of Kudla-Rapoport-Yang which gives a formula for the arithmetic degree of the moduli space of CM elliptic curves together with a special endomorphism of a specified degree. Our extension is to the moduli space of QM abelian surfaces with CM together with a special endomorphism of a specified QM degree.

Some remarks added about a related result of Kudla-Yang