K3 surfaces with involution, equivariant analytic torsion, and automorphic forms on the moduli space

摘要

In this paper, we introduce an invariant of a K3 surface with Z_2-action equipped with a Z_2-invariant K?hler metric, which we obtain using the equivariant analytic torsion of the trivial line bundle. This invariant is shown to be independent of the choice of the Kahler metric. It can be viewed as a function on the moduli space of K3 surfaces with involution. The main result of this paper is that this function can be identified with an automorphic form, which characterizes the discriminant locus. In particular, we show that the Ray–Singer analytic torsion of the trivial line bundle on an Enriques surface with Ricci-flat Kahler metric is given by the value of the norm of the Borcherds -function at its period point.