Decay of cosmic global string loops

Abstract

We numerically study the decay of cosmic global string loops due to radiation of Goldstone bosons and massive scalar ($\ensuremath{\chi}$) particles. The length of loops we study range from 200 to 1000 times the width of the string core. We find that the lifetime of a loop is $\ensuremath{\approx}1.4L$. The energy spectrum of Goldstone boson radiation has a ${k}^{\ensuremath{-}1}$ falloff, where $k$ is the wave number, and a sharp peak at $k\ensuremath{\approx}{m}_{\ensuremath{\chi}}/2$, where ${m}_{\ensuremath{\chi}}$ is the mass of $\ensuremath{\chi}$. The latter is a new feature and implies a peak at high energies (MeV-GeV) in the cosmological distribution of QCD axions.

Topics & Concepts