Naked Singularities in Four-Dimensional String Backgrounds

TL;DR

This paper demonstrates how deformations of gauged nonlinear sigma models can produce four-dimensional string backgrounds with naked singularities, expanding the understanding of singularity formation in string theory.

Contribution

It introduces a method to generate four-dimensional string backgrounds with naked singularities via deformations of conformal coset models.

Findings

Naked singularities can form in certain four-dimensional string backgrounds.

Deformations of gauged sigma models correspond to marginal operators in conformal field theory.

A class of curved spacetime solutions with naked singularities is constructed.

Abstract

It is shown that gauged nonlinear sigma models can be always deformed by terms proportional to the field strength of the gauge fields (nonminimal gauging). These deformations can be interpreted as perturbations, by marginal operators, of conformal coset models. When applied to the SL(2,R)*SU(2)/[U(1)*U(1)] WZWN model, a large class of four-dimensional curved spacetime backgrounds are obtained. In particular, a naked singularity may form at a time when the volume of the universe is different from zero.