Calculation of the dark matter relic density in supersymmetric models including SUSY-QCD corrections

par Dr Bjoern Herrmann (U. Wuerzburg)

mardi 20 janv. 2009, 14:30 → 15:30 Europe/Paris

Amphi M. Perey (IPHC/DRS)

The calculation of the dark matter relic density is an interesting tool to constrain the parameter space of supersymmetric models providing additional information with respect to collider, low-energy, and electroweak precision data. After the launch of the PLANCK satellite in a near future, the current observational limits on the relic density, today mainly based on the latest WMAP results, will become much more precise. In consequence, it is important to achieve more precise theoretical predictions in order to keep up with the experimental improvements. This makes it necessary to include radiative corrections to the dark matter annihilation cross section that governes the calculation of the relic density. After an introduction to supersymmetric dark matter and the calculation of its relic density, I will focus on the case of minimal supergravity (mSUGRA) where the dark matter candidate is the lightest of the four neutralinos. In the cosmologically favoured regions of the corresponding parameter space, the annihilation into heavy quark-antiquark pairs is dominant with respect to other possible final states. The leading corrections to be included arise therefore from QCD and SUSY-QCD loop diagrams. I will present the first calculation of these supersymmetric QCD corrections to neutralino annihilation into massive quarks with the full O(alpha_s) supersymmetric QCD corrections, including the known resummation of logarithmically enhanced terms. Their numerical impact on the extraction of SUSY mass parameters from cosmological data is shown to be sizeable so that the preferred regions of the parameter space are modified and the corrections must be included in common analysis tools.

Slides herrmann.pdf