Supersymmetric leptogenesis

Abstract

We study leptogenesis in the supersymmetric standard model plus the seesaw.\nWe identify important qualitative differences that characterize supersymmetric\nleptogenesis with respect to the non-supersymmetric case. The lepton number\nasymmetries in fermions and scalars do not equilibrate, and are related via a\nnon-vanishing gaugino chemical potential. Due to the presence of new anomalous\nsymmetries, electroweak sphalerons couple to winos and higgsinos, and QCD\nsphalerons couple to gluinos, thus modifying the corresponding chemical\nequilibrium conditions. A new constraint on particles chemical potentials\ncorresponding to an exactly conserved $R$-charge, that also involves the number\ndensity asymmetry of the heavy sneutrinos, appears. These new ingredients\ndetermine the $3\\times 4$ matrices that mix up the density asymmetries of the\nlepton flavours and of the heavy sneutrinos. We explain why in all temperature\nranges the particle thermodynamic system is characterized by the same number of\nindependent quantities. Numerical differences with respect to usual treatment\nremain at the ${\\cal O}(1)$ level.\n