Cosmic String Dynamics and Evolution in Warped Spacetime

TL;DR

This paper investigates the dynamics of cosmic strings in warped spacetimes, revealing that classical damping mechanisms are insufficient for stabilization at the throat, which impacts superstring intercommuting probabilities.

Contribution

It provides a detailed analysis of string motion in warped backgrounds, showing classical damping is ineffective for stabilization, a novel insight into string evolution in such geometries.

Findings

Strings experience deflections and bounces, not damping.

Classical mechanisms like Hubble friction are ineffective internally.

Implications for cosmic superstring intercommuting probabilities.

Abstract

We study the dynamics and evolution of Nambu-Goto strings in a warped spacetime, where the warp factor is a function of the internal coordinates giving rise to a `throat' region. The microscopic equations of motion for strings in this background include potential and friction terms, which attract the strings towards the bottom of the warping throat. However, by considering the resulting macroscopic equations for the velocities of strings in the vicinity of the throat, we note the absence of enough classical damping to guarantee that the strings actually reach the warped minimum and stabilise there. Instead, our classical analysis supports a picture in which the strings experience mere deflections and bounces around the tip, rather than strongly damped oscillations. Indeed, 4D Hubble friction is inefficient in the internal dimensions and there is no other classical mechanism known, which could provide efficient damping. These results have potentially important implications for the intercommuting probabilities of cosmic superstrings.