Thermal decoupling in WIMP dark matter models with long-range interactions

Who: Torsten Bringmann (University of Hamburg)
When: Monday, March 4, 2013 at 14:15
Where: U49

 

The chemical decoupling of weakly interacting massive particles (WIMPs) in the early universe determines their relic density today. Kinetic decoupling, on the other hand, happens only considerably later and sets a scale that can directly be translated into a small-scale cutoff in the spectrum of matter density fluctuations, corresponding to the least massive protohalos that can form. In models where the WIMPs are subject to a long-range interaction mediated by a light force carrier, these two processes in general cannot be separated anymore. A rich phenomenology results, ranging from a potentially new era of dark matter annihilation around and after kinetic decoupling to much larger cutoff masses than for standard dark matter candidates like the MSSM neutralino. In this talk, I will review the formalism that allows to calculate both the chemical and kinetic decoupling process to a high precision even in this case. As an application, I will illustrate the main differences to the standard case in terms of simple toy models and demonstrate that such models might even provide a simultaneous solution to all small-scale problems of LambdaCDM cosmology.

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