The arithmetic Hodge Index Theorem and rigidity of dynamical systems over function fields

TL;DR

This paper extends the arithmetic Hodge Index Theorem to projective varieties over function fields of transcendence degree one and applies it to establish a rigidity theorem for points of canonical height zero in dynamical systems.

Contribution

It generalizes the Hodge Index Theorem to higher-dimensional varieties over function fields and proves a new rigidity theorem for canonical height zero points in dynamical systems.

Findings

Extended Hodge Index Theorem to projective varieties over function fields.

Proved a rigidity theorem for canonical height zero points in dynamical systems.

Generalized rigidity results for preperiodic points over finite fields.

Abstract

In one of the fundamental results of Arakelov's arithmetic intersection theory, Faltings and Hriljac (independently) proved the Hodge Index Theorem for arithmetic surfaces by relating the intersection pairing to the negative of the N\'eron-Tate height pairing. More recently, Moriwaki and Yuan-Zhang generalized this to higher dimension. In this work, we extend these results to projective varieties over transcendence degree one function fields. The new challenge is dealing with non-constant but numerically trivial line bundles coming from the constant field via Chow's $K/k$-trace functor. As an application of the Hodge Index Theorem, we also prove a rigidity theorem for the set of canonical height zero points of polarized algebraic dynamical systems over function fields. For function fields over finite fields, this gives a rigidity theorem for preperiodic points, generalizing previous work of Mimar, Baker-DeMarco, and Yuan-Zhang.