Projects per year
Abstract
We study dark matter production by decaying topological defects, in particular cosmic strings. In topological defect or "topdown" (TD) scenarios, the dark matter injection rate varies as a power law with time with exponent p4. We find a formula in closed form for the yield for all p < 3/2, which accurately reproduces the solution of the Boltzmann equation. We investigate two scenarios (p = 1, p = 7/6) motivated by cosmic strings which decay into TeVscale states with a high branching fraction into dark matter particles. For dark matter models annihilating either by swave or pwave, we find the regions of parameter space where the TD model can account for the dark matter relic density as measured by Planck. We find that topological defects can be the principal source of dark matter, even when the standard freezeout calculation underpredicts the relic density and hence can lead to potentially large "boost factor" enhancements in the dark matter annihilation rate. We examine dark matter modelindependent limits on this scenario arising from unitarity and discuss example modeldependent limits coming from indirect dark matter search experiments. In the four cases studied, the upper bound on Gμ for strings with an appreciable channel into TeVscale states is significantly more stringent than the current Cosmic Microwave Background limits
Original language  English 

Article number  037 
Number of pages  21 
Journal  Journal of Cosmology and Astroparticle Physics 
Volume  2014 
DOIs  
Publication status  Published  18 Mar 2014 
Keywords
 Cosmic strings
 dark matter theory
 domain walls
 monopoles
Projects
 1 Finished

Theoretical Particle Physics Consortium Sussex – Royal Holloway 20142017
Science and Technology Facilities Council
1/10/14 → 30/09/17
Project: Research