Fano hypersurfaces with no finite order birational automorphisms

Abstract

We use the specialization homomorphism for the birational automorphism group to study finite order birational automorphisms. For a family of varieties over a DVR, we prove that a birational automorphism of order coprime to the residue characteristic cannot specialize to the identity. As an application, we show that very general $n$-dimensional hypersurfaces of degree $d\ge 5\lceil (n+3)/6\rceil$ have no finite order birational automorphisms.

10 pages