# Decay of Cosmic String Loops Due to Particle Radiation

## TL;DR

This paper investigates how cosmic string loops decay via particle radiation and gravitational waves, revealing that particle emission dominates for small loops and gravitational radiation for larger ones, impacting cosmological constraints.

## Contribution

It provides the first detailed field theory simulations of cosmic string loop decay, quantifying the scaling of decay times due to particle radiation and gravitational waves.

## Key findings

- Particle radiation decay time scales as L^2.
- Gravitational radiation decay time scales as L.
- Particle emission dominates for small loops.

## Abstract

Constraints on the tension and the abundance of cosmic strings depend crucially on the rate at which they decay into particles and gravitational radiation. We study the decay of cosmic string loops in the Abelian-Higgs model by performing field theory simulations of loop formation and evolution. We find that our set of string loops emit particle radiation primarily due to kink collisions, and that their decay time due to these losses is proportional to $L^p$ with $p \approx 2$ where $L$ is the loop length. In contrast, the decay time to gravitational radiation scales in proportion to $L$, and we conclude that particle emission is the primary energy loss mechanism for loops smaller than a critical length scale, while gravitational losses dominate for larger loops.