On the Kawaguchi--Silverman Conjecture for birational automorphisms of irregular varieties

Abstract

We study the main open parts of the Kawaguchi--Silverman Conjecture, asserting that for a birational self-map $f$ of a smooth projective variety $X$ defined over $\overline{\mathbb{Q}}$, the arithmetic degree ${\alpha }_f(x)$ exists and coincides with the first dynamical degree ${\delta }_f$ for any $\overline{\mathbb{Q}}$-point $x$ of $X$ with a Zariski dense orbit. Among other results, we show that this holds when $X$ has Kodaira dimension zero and irregularity $q(X)\ge \dim X-1$ or $X$ is an irregular threefold (modulo one possible exception). We also study the existence of Zariski dense orbits, with explicit examples.

Final form to appear in Forum Mathematicum, DOI: 10.1515/forum-2023-0350