Dilatonic global strings

TL;DR

This paper investigates the effects of dilaton coupling on global strings in superstring gravity, revealing conditions for singular and non-singular spacetimes, and introduces a time-dependent string/anti-string configuration causing dimensional compactification.

Contribution

It analyzes global string solutions with arbitrary dilaton coupling, highlighting differences between massive and massless dilaton cases and presenting a novel non-singular string/anti-string setup.

Findings

Massive dilaton leads to non-singular spacetime solutions.

Massless dilaton generally results in singular spacetimes.

A new time-dependent string/anti-string configuration causes large-scale dimensional compactification.

Abstract

We examine the field equations of a self-gravitating global string in low energy superstring gravity, allowing for an arbitrary coupling of the global string to the dilaton. Massive and massless dilatons are considered. For the massive dilaton the spacetime is similar to the recently discovered non-singular time-dependent Einstein self-gravitating global string, but the massless dilaton generically gives a singular spacetime, even allowing for time-dependence. We also demonstrate a time-dependent non-singular string/anti-string configuration, in which the string pair causes a compactification of two of the spatial dimensions, albeit on a very large scale.