On the interplay between ‘high’ and ‘low’ energy CP violation in flavoured leptogenesis

Abstract

The possible interplay in ‘flavoured’ leptogenesis between the ‘low energy’ CP violation originating from the PMNS neutrino mixing matrix U, and the ‘high energy’ CP-violation which can be present in the matrix of neutrino Yukawa couplings, λ, and can manifest itself only in ‘high’ energy scale processes, is discussed. The results reported are obtained for type I see-saw model with three heavy right-handed Majorana neutrinos having hierarchical spectrum. It is shown that in the case of inverted hierarchical light neutrino mass spectrum, there exist regions in the corresponding leptogenesis parameter space where the relevant ‘high energy’ phases have large CP-violating values, but the purely ‘high energy’ contribution in Yb plays a sub-dominant role in the production of baryon asymmetry compatible with the observations.