Gravitational back-reaction near cosmic string kinks and cusps

TL;DR

This paper analyzes the leading-order gravitational back-reaction effects on cosmic strings near kinks and cusps, revealing divergence behaviors and energy loss mechanisms that influence string dynamics.

Contribution

It provides the first detailed calculation of how gravitational back-reaction affects cosmic string features like kinks and cusps, including divergence rates and energy dissipation.

Findings

Back-reaction near kinks diverges as inverse cube root of distance.

Near cusps, the effect diverges inversely linearly with distance.

Energy loss near cusps diverges logarithmically with approach distance.

Abstract

We find the leading-order effect of gravitational back-reaction on cosmic strings for points near kinks and cusps. Near a kink, the effect diverges as the inverse cube root of the distance to the kink, and acts in a direction transverse to the worldsheet. Over time the kink is rounded off, but only regions fairly close to the kink are significantly affected. Near cusps, the effect diverges inverse linearly with the distance to the cusp, and acts against the direction of the cusp motion. This results in a fractional loss of string energy that diverges logarithmically with the distance of closest approach to the cusp.