From weak-scale observables to leptogenesis

Thermal leptogenesis is an attractive mechanism for generating the baryonasymmetry of the Universe. However, in supersymmetric models, the parameterspace is severely restricted by the gravitino bound on the reheat temperature$T_{RH}$. For hierarchical light neutrino masses, it is shown that thermalleptogenesis {\it can} work when $T_{RH} \sim 10^{9} $ GeV. The low-energyobservable consequences of this scenario are $ BR(\tau \to \ell \gamma) \sim10^{-8} - 10^{-9} $. For higher $T_{RH}$, thermal leptogenesis works in alarger area of parameter space, whose observable consequences are moreambiguous. A parametrisation of the seesaw in terms of weak-scale inputs isused, so the results are independent of the texture chosen for the GUT-scaleYukawa matrices.Comment: a few references adde