Vacuumless topological defects in Lyra geometry

TL;DR

This paper investigates the gravitational effects of vacuumless topological defects, specifically global strings and monopoles, within Lyra geometry, revealing unique repulsive and attractive behaviors not seen in general relativity.

Contribution

It derives the metrics for vacuumless global string and monopole in Lyra geometry under weak field approximation, highlighting their distinct gravitational effects.

Findings

Global string exhibits repulsive gravity.

Global monopole exerts attractive gravity.

Differences from general relativity are demonstrated.

Abstract

Few years ago, Cho and Vilenkin have proposed that topological defects can arise in symmetry breaking models without having degenerate vacua. These types of defects are known as vacuumless defects. In the present work, the gravitational field of a vacuumless global string and global monopole have been investigated in the context of Lyra geometry. We find the metric of the vacuumless global string and global monopole in the weak field approximations. It has been shown that the vacuumless global string can have repulsive whereas global monopole exerts attractive gravitational effects on a test particle. It is dissimilar to the case studied in general relativity.