Surfaces generating the even primal cohomology of an abelian fivefold

Abstract

Given a very general abelian fivefold $A$ and a principal polarization $\Theta \subset A$, we construct surfaces generating the algebraic part of the middle cohomology $H^4(\Theta, {\mathbb Q})$, and determine the intersection pairing between these surfaces. In particular, we obtain a new proof of the Hodge conjecture for $H^4(\Theta, {\mathbb Q})$ and show that it contains a copy of the root lattice of $E_6$.