K3 surfaces associated to a cubic fourfold

Abstract

Let $X\subset {\P }^5$ be a smooth cubic fourfold. A well known conjecture asserts that $X$ is rational if and only if there an Hodge theoretically associated K3 surface $S$. The surface $S$ can be associated to $X$ in two other different ways. If there is an equivalence of categories $\sA_X \simeq D^b(S,α)$ where $\sA_X$ is the Kuznetsov component of $D^b(X)$ and $\alpha$ is a Brauer class, or if there is an isomorphism between the transcendental motive $t(X)$ and the (twisted ) transcendental motive of a K3 surface$S$. In this note we consider families of cubic fourfolds with a finite group of automorphisms and describe the cases where there is an associated K3 surface in one of the above senses.

23 pages Revised version.Added new results and more references