Thermal decoupling of WIMPs from first principles

By T. Bringmann, S. Hofmann. 2006

174 citations recorded by the source corpus.

Weakly interacting massive particles (WIMPs) are arguably the most natural dark matter candidates from a particle physics point of view. After their number density has frozen out in the early universe, thereby setting their relic density today, WIMPs are still kept very close to thermal equilibrium by scattering events with standard model particles. The complete decoupling from the thermal bath happens as late as at temperatures of around ∼1−10 MeV and provides an important cosmological scale that can directly be translated into a small scale cut-off of the spectrum of matter density fluctuations. We present here a full analytic treatment of the kinetic decoupling process from first principles. This allows an exact determination of the decoupling scale, for arbitrary WIMP candidates and any scattering amplitude. As an application, we consider the situation of the lightest supersymmetric particle as well as the lightest Kaluza–Klein particle that arises in theories with universal extra dimensions; furthermore, we show that our formalism can also easily be applied to, e.g., the evolution of the non-relativistic electrons into the recombination regime. Finally, we comment on the impacts for the smallest gravitationally bound structures and the prospects for the indirect detection of dark matter.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/12a3538fb6b6f7a8741c6a46609e5632d60b8ac0

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Citations in the corpus

Lectures on Dark Matter Physics (2016, background): “Detailed modeling of these effects is somewhat involved (see the review [51] and references therein), but the net effect is to strongly suppress the perturbation spectrum below some characteristic wavenumber (or above some free-streaming length).”
Hidden charged dark matter (2009, background): “[54, 55] to determine the temperature of kinetic decoupling for the dark matter particle.”
Constraints on dark matter annihilation in clusters of galaxies with the Fermi large area telescope (2010, background): “For typical thermally produced WIMP models, these substructures are expected to exist down to cutoff scales of between 10 and 10 Earth masses [32–34].”
ETHOS - an effective theory of structure formation: dark matter physics as a possible explanation of the small-scale CDM problems (2015, background): “Note that the above relation between Mcut and Tkd specifically assumes the definition of Tkd proposed in Bringmann & Hofmann (2007); other definitions of Tkd would change it by a constant factor Bringmann et al. (2016).”