Zhang's Conjecture and the Effective Bogomolov Conjecture over function fields

TL;DR

This paper proves the Effective Bogomolov Conjecture over function fields of characteristic 0 by establishing Zhang's Conjecture on invariants of metrized graphs, extending known results beyond special cases.

Contribution

It proves Zhang's Conjecture and the Effective Bogomolov Conjecture over general function fields, linking invariants of metrized graphs to the tau constant and extending previous results.

Findings

Proved the Effective Bogomolov Conjecture over characteristic 0 function fields.

Related invariants in Zhang's Conjecture to the tau constant of metrized graphs.

Provided a new proof of the slope inequality for Faltings heights.

Abstract

We prove the Effective Bogomolov Conjecture, and so the Bogomolov Conjecture, over a function field of characteristic 0 by proving Zhang's Conjecture about certain invariants of metrized graphs. In the function field case, these conjectures were previously known to be true only for curves of genus at most 4 and a few other special cases. We also either verify or improve the previous results. We relate the invariants involved in Zhang's Conjecture to the tau constant of metrized graphs. Then we use and extend our previous results on the tau constant. By proving another Conjecture of Zhang, we obtain a new proof of the slope inequality for Faltings heights on moduli space of curves.