Low-scale leptogenesis with Dirac phase CP-violation

The freeze-in scenario of leptogenesis via oscillations within the type-I seesaw model with two quasi-degenerate heavy Majorana neutrinos N1,2 can be viable in the mass range M~ (0.1-100)\,GeV even when the Dirac phase δ of the Pontecorvo-Maki-Nakagawa-Sakata neutrino mixing matrix is the only source of CP-violation in the leptonic sector and in leptogenesis. In particular, viable leptogenesis with Dirac phase CP-violation is compatible with N1,\,2 total squared coupling to the Standard Model leptons within the reach of future planned and proposed experiments. Moreover, the parameter space differs from the one associated with the Casas-Ibarra sources of CP-violation. Future precise determination of δ and/or the N1,2 couplings to the Standard Model leptons could establish whether, within the context of low-scale leptogenesis, the Dirac phase alone can be responsible for the present baryon asymmetry of the Universe.