On a conjecture of Voisin on the gonality of very general abelian varieties

Abstract

We study orbits for rational equivalence of zero-cycles on very general abelian varieties by adapting a method of Voisin to powers of abelian varieties. We deduce that, for $k$ at least $3$, a very general abelian variety of dimension at least $2k-2$ has covering gonality greater than $k$. This settles a conjecture of Voisin. We also discuss how upper bounds for the dimension of orbits for rational equivalence can be used to provide new lower bounds on other measures of irrationality. In particular, we obtain a strengthening of the Alzati-Pirola bound on the degree of irrationality of abelian varieties.

Several changes were made to the presentation and notation. Some mistakes and an erroneous attribution were fixed. The appendix was removed. The proof of the main result was clarified. 27 pages. Comments welcome