Axion/axino dark matter: reconciling thermal leptogenesis with the gravitino problem

by Andre Lessa (Oklahoma U.)

Friday 17 Sept 2010, 11:00 → 12:00 Europe/Paris

Successful implementation of thermal leptogenesis requires re-heat temperatures T_R>10^9 GeV, in apparent conflict with SUSY models with TeV-scale gravitinos, which require much lower T_R in order to avoid Big Bang Nucleosynthesis (BBN) constraints. We show that mixed axion/axino dark matter can reconcile thermal leptogenesis with the gravitino problem in models with m(gravitino)>30 TeV, a rather high Peccei-Quinn breaking scale and an initial mis-alignment angle theta_i < 1. We calculate axion and axino dark matter production from four sources, and impose BBN constraints on long-lived gravitinos and neutralinos. Moreover, we discuss several SUSY models which naturally have gravitino masses of the order of tens of TeV. We find that T_R ~ 10^10 to 10^12 GeV can easily be achieved in, e.g., effective SUSY and in models based on mixed moduli-anomaly mediation.