From weak-scale observables to leptogenesis

Thermal leptogenesis is an attractive mechanism for generating the baryon asymmetry of the Universe. However, in supersymmetric models, the parameter space is severely restricted by the gravitino bound on the reheat temperature TRH . For hierarchical light neutrino masses, it is shown that thermal leptogenesis can work when TRH ∼ 10 GeV. The lowenergy observable consequences of this scenario are BR(τ → lγ) ∼ 10 − 10. For higher TRH , thermal leptogenesis works in a larger area of parameter space, whose observable consequences are more ambiguous. A parametrisation of the seesaw in terms of weak-scale inputs is used, so the results are independent of the texture chosen for the GUT-scale Yukawa matrices.