SUSY07

Effect of radiative corrections at order alpha_s to neutralino annihilation processes on the cold dark matter relic density

27 Jul 2007, 17:50

20m

Lehmann-Auditorium (Karlsruhe University)

Parallel Talk Cosmology and Astrophysics Cosmology 4

Speaker

Mr Björn Herrmann (LPSC Grenoble)

Description

Supersymmetry (SUSY) is the most economical and best studied possible extension of the Standard Model of particle physics. In particular, the lightest of the four neutralinos is a good candidate for the cold dark matter, which accounts for about 25% of our universe and whose nature remains at present unknown. The possibility to compute the neutralino relic density within a given model and to compare to cosmological data provides an interesting possibility to constrain the SUSY parameter space and to obtain complementary information with respect to collider experiments. As new experiments will deliver more precise cosmological data in a near future, radiative corrections to the neutralino pair annihilation cross section become important within this context. We compute the (SUSY-)QCD corrections contributing to the annihilation cross section and we evaluate their effect on the cross section itself as well as on the neutralino relic density with respect to cosmological constraints. We present an extensive analysis of the (SUSY-)QCD corrections to neutralino pair annihilation processes in different cosmological regions of the mSUGRA parameter space. In a first step, we study the annihilation into a pair b\bar{b} through pseudoscalar Higgs exchange, which dominates in the cosmological "A-funnel" region caracterized by large tan(beta). Our study confirms the importance of radiative corrections, which decrease the annihilation cross section by about 50% for the QCD part, and by up to another 10% for the SUSY-QCD part. In consequence, the neutralino relic density increases, and the "A-funnel" slope agreeing with cosmological data is shifted to smaller SUSY masses. The second step of our project consists of a similar study for neutralino pair annihilation into a quark-antiquark pair through Z-boson or squark exchange, which are the dominant processes in the cosmological "bulk" region. We compute all relevant (SUSY-)QCD corrections and we evaluate their effect on the annihilation cross section and the cosmologically favoured regions of the SUSY parameter space.

Presentation materials

Paper

http://arxiv.org/pdf/0709.2232

Slides

herrmann_dm.pdf.pdf