Year: 2010
Type: article
Abstract: We investigate the relation between non-unitarity of the leptonic mixing matrix and leptogenesis. We discuss how all parameters of the canonical type-I seesaw mechanism can, in principle, be reconstructed from the neutrino mass matrix and the deviation of the effective low-energy leptonic mixing matrix from unitary. When the mass M ′ of the lightest right-handed neutrino is much lighter than the masses of the others, we show that its decay asymmetries within flavour-dependent leptogenesis can be expressed in terms of two contributions, one depending on the unique dimension five ( d = 5) operator generating neutrino masses and one depending on the dimension six ( d = 6) operator associated with non-unitarity. In low-energy seesaw scenarios where small lepton number violation explains the smallness of neutrino masses, the lepton number conserving d = 6 operator contribution generically dominates over the d = 5 operator contribution which results in a strong enhancement of the flavour-dependent decay asymmetries without any resonance effects. To calculate the produced final baryon asymmetry, the flavour equilibration effects directly related to non-unitarity have to be taken into account. In a simple realization of this non-unitarity driven leptogenesis , the lower bound on M′ is found to be about 10 8 GeV at the onset of the strong washout regime, more than one order of magnitude below the bound in “standard” thermal leptogenesis.
Source: Journal of High Energy Physics
Authors: Stefan Antusch, Steve Blanchet, Mattias Blennow, Enrique Fernandez-Martinez
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid:
OpenAlex ID: W1989356696