Convexity of complements of limit sets for holomorphic foliations on surfaces

TL;DR

This paper proves that for certain holomorphic foliations on compact Kähler surfaces, the complement of the limit set is a modified Stein domain, using curvature metrics and plurisubharmonic functions.

Contribution

It establishes the convexity of complements of limit sets for holomorphic foliations with specific singularities, extending Brunella's methods to singular contexts.

Findings

Complement of the limit set is a Stein domain modification.

Constructed a positive curvature metric near the limit set.

Developed a plurisubharmonic exhaustion function for the complement.

Abstract

Let $\mathcal F$ be a holomorphic foliation on a compact K\'ahler surface with hyperbolic singularities and no foliation cycle. We prove that if the limit set of $\mathcal F$ has zero Lebesgue measure, then its complement is a modification of a Stein domain. The proof consists in building, in several steps, a metric of positive curvature for the normal bundle of $\mathcal F$ near the limit set. Then we construct a proper strictly plurisubharmonic exhaustion function for the complement of the limit set, by adapting Brunella's ideas to our singular context. The arguments hold more generally when the limit set is thin, a property relying on Brownian motion.