SuperWIMP dark matter scenario in light of WMAP

Abstract

The heavy gravitinos in minimal supergravity (mSUGRA) models couple gravitionally and can naturally be the Superweakly Interacting Massive Particle (SuperWIMP). As plausible candidates for the cold dark matter in the universe, such gravitino SuperWIMPs can naturally evade the current dark matter detection experiments due to their superweak couplings. However, this scenario must subject to the constraints from the Big Bang nucleosynthesis (BBN) predictions for light element abundances as well as the Wilkinson Mircrowave Anisotropy Probe (WMAP) data for the relic density. Our study shows that requiring BBN predictions to agree with the WMAP data of light element abundances can impose upper and lower mass bounds for both the gravitino and the next-to-lightest supersymmetric particle (NLSP). From a scan over the mSUGRA parameter space subjected to the BBN constraints and the WMAP data, we find that in the neutralino NLSP case, the low tan-beta (< 40) region as well as the region accessible at CERN Large Hadron Colldier (LHC) will be severely restrained.