Stringy Domain Walls and Other Stringy Topological Defects

TL;DR

This paper explores stringy topological defects, especially domain walls, within string compactifications, providing explicit solutions and introducing a new concept of vacuum degeneracy in supersymmetric contexts.

Contribution

It identifies and constructs stringy domain walls using target space modular invariance, offering explicit solutions and extending the concept of vacuum degeneracy in supersymmetric string vacua.

Findings

Found topologically stable stringy domain walls in string compactifications.

Presented explicit supersymmetric solutions saturating the Bogomol'nyi bound.

Introduced a new notion of vacuum degeneracy for supersymmetric vacua.

Abstract

We point out that the moduli sector of the $(2,2)$ string compactification with its nonperturbatively preserved non-compact symmetries is a framework to study global topological defects. Based on the target space modular invariance of the nonperturbative superpotential of the four-dimensional $N=1$ supersymmetric string vacua, topologically stable stringy domain walls are found. Explicit supersymmetric solutions for the modulus field and the metric, which saturate the Bogomol'nyi bound, are presented. They interpolate between {\it non-degenerate} vacua. As a corollary, this defines a new notion of vacuum degeneracy of supersymmetric vacua. Nonsupersymmetric stringy domain walls are discussed as well. The moduli sectors with more than one modulus and the non-compact continous symmetry preserved allow for global monopole-type and texture-type configurations.