Nonsingular global string compactifications

TL;DR

This paper explores a novel higher-dimensional spacetime model with two infinite extra dimensions, demonstrating nonsingular solutions using global strings and analyzing their potential to address the hierarchy problem.

Contribution

It introduces a new class of nonsingular compactification solutions with global strings, extending previous models like Randall-Sundrum and Cohen-Kaplan.

Findings

Existence of nonsingular static solutions with negative cosmological constant.

Time-dependent nonsingular solutions without cosmological constant.

Comparison with established models and implications for hierarchy problem.

Abstract

We consider an exotic `compactification' of spacetime in which there are two infinite extra dimensions, using a global string instead of a domain wall. By having a negative cosmological constant we prove the existence of a nonsingular static solution using a dynamical systems argument. A nonsingular solution also exists in the absence of a cosmological constant with a time-dependent metric. We compare and contrast this solution with the Randall-Sundrum universe and the Cohen-Kaplan spacetime, and consider the options of using such a model as a realistic resolution of the hierarchy problem.