On the connection between low-energy leptonic CP-violation and leptogenesis
Monday 20 October, 2:30 pm, Curia II
Silvia Pascoli  (UCLA)

abstract:
The origin of the matter-antimatter asymmetry is one of the most important questions in cosmology. As the Standard Model cannot provide a satisfactory explanation of the baryon asymmetry, at present one of the most studied mechanisms to account for it is leptogenesis.
The latter is particularly appealing because it takes place in the context of the see-saw mechanism, which at the same time naturally  explains the smallness of neutrino masses.
Establishing a connection between the parameters at low energy (neutrino masses, mixing angles and CP-violating phases), and at high energy (relevant in leptogenesis) has gathered
a great interest in the last few years. As the parameters in the see-saw models are more than the ones which are present in the low-energy effective theory and are in principle measurable
in the present and future experiments, in general, there is no direct link between the two.
However most specific models allow for such a connection. I will discuss in general the possibility to establish such a connection. Furthermore I will present two models in which the link is studied in detail. In the first model a hierarchical see-saw model has been studied,
founding that the effective Majorana mass parameter in neutrinoless double beta decay depends on the phases relevant for leptogenesis while there is no direct connection between the magnitude of CP-violation effects in neutrino oscillations and leptogenesis. The second model considered is the case of quasi-degenerate neutrino mass spectrum, which is going to be tested in the next future. In the context of SUSY GUT models,  in presence of a generic complex Yukawa coupling between light and heavy neutrinos, the rate for  flavour violating charged leptons decays is found to be within the reach of present and future experiments.
Furthermore as the number of relevant parameters at leading order  is reduced, it is possible to link the low energy parameters to the ones which play a role in leptogenesis.