Generality of Topological Inflation

TL;DR

This paper demonstrates that topological inflation can begin in highly inhomogeneous regions, challenging previous claims that large inhomogeneity prevents inflation, by leveraging the stability of false vacuum in defect cores.

Contribution

It shows that topological inflation can occur even with significant inhomogeneity and large gradient energy, provided the vacuum expectation value is sufficiently large.

Findings

Inflation starts in defect cores despite small size and high gradient energy.

False vacuum stability enables inflation in inhomogeneous regions.

Large vacuum expectation value is crucial for topological inflation.

Abstract

Many authors claimed that a large initial inhomogeneity prevents the onset of inflation and therefore inflation takes place only if the scalar field is homogeneous or appropriately chosen over the horizon scale. We show that those arguments do not apply to topological inflation. The core of a defect starts inflation even if it has much smaller size than the horizon and much larger gradient energy than the potential, as long as the vacuum expectation value is large enough ($\gtrsim0.3\mpl$) and the core is not contracting initially. This is due to stability of false vacuum.