Implications of Target Space Duality

TL;DR

This paper explores how target space duality influences string vacua, revealing that nonperturbative effects can break supersymmetry, induce instabilities, and lead to stable domain wall solutions with significant physical implications.

Contribution

It analyzes nonperturbative effects of target space duality on string vacua, including supersymmetry breaking, vacuum instability, and the existence of stable domain walls.

Findings

Nonperturbative superpotential removes vacuum degeneracy.

Supersymmetry is generically broken with negative cosmological constant.

Stable supersymmetric domain walls are identified.

Abstract

Based on the assumption that the target space duality ($T\to 1/T$) is preserved even nonperturbatively, the properties of static string vacua are studied. A discussion of the effective four-dimensional supergravity action based on target-space modular symmetry $SL(2,{\bf Z})$ is presented. The nonperturbative superpotential removes the vacuum degeneracy with respect to the compactification modulus ($T$) generically breaks supersymmetry with negative cosmological constant. Charged matter fields get negative $(mass)^2$ signalling an additional instability of string vacuum and the blowing up of orbifold singularities. In addition for a class of modularly invariant potentials topologically stable stringy domain walls of nontrivial compaction modulus field configuration are found. They are supersymmetric solutions, thus saturating the Bogomolnyi bound. Their physical implications are discussed.