Quantization of heterotic strings in a Goedel/Anti de Sitter spacetime and chronology protection

TL;DR

This paper constructs and analyzes a heterotic string background with a Goedel-like deformation of AdS3, exploring its spectrum, stability, and implications for closed timelike curves and chronology protection.

Contribution

It introduces an exactly marginal deformation of heterotic string theory that results in a Goedel-like spacetime, and examines its spectrum and stability properties.

Findings

The Goedel-like deformation is an exact string background.

Long strings destabilize the background, leading to potential chronology violations.

A modified background may prevent closed timelike curves via string condensation.

Abstract

We show that a Goedel-like deformation of AdS3 in heterotic string theory can be realized as an exact string background. Indeed this class of solutions is obtained as an exactly marginal deformation of the conformal field theory describing the NS5/F1 heterotic background. It can also be embedded in type II superstrings as a Kaluza-Klein reduction. We compute the spectrum of this model as well as the genus one modular invariant partition function. We discuss the issue of closed timelike curves and the propagation of long strings. They destabilize completely the background, although we construct another exact string background that may describe the result of the condensation of these long strings. Closed timelike curves are avoided in that case.