Gravitino, dark matter candidate and BBN

par Sean Bailly (LAPTH)

mardi 5 avr. 2011, 11:00 → 12:00 Europe/Paris

Petit amphi (LAPTH)

I will present a simple scenario in the CMSSM with the gravitino as the lightest supersymmetric particle (LSP) and the stau as the next-to-lightest supersymmetric particle (NLSP). Assuming the conservation of R-parity, the LSP is stable and a good candidate for dark matter. The gravitino is produced in the early universe in scattering processes during the reheating era and through the decay of the stau. If the NLSP decay occurs during Big Bang Nucleosynthesis (BBN), it is possible to address the issue of the lithium problems in the BBN. The are discrepancies between observed abundances and theoretical predictions for lithium-6 and lithium-7. I will show that it is possible to solve both lithium problems and simultaneously obtain the correct relic density for dark matter. The derived constraints are an upper bound on the reheating temperature which is much lower than leptogenesis requirements. Furthermore, the SUSY mass spectrum is quite heavy and well out of LHC reach. I will talk about a non-standard cosmological scenario with a modified Hubble parameter which relaxes these constraints and allows solutions for the dark matter relic density or the lithium problems.

Slides Bailly