2003/12/01 by Michele Frigerio, Frigerio, Michele
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/0312023
20 pages, latex, 1 figure. References added
arxiv created 2004/04/07 · arxiv updated 2009/12/01
Inverting the type-I seesaw formula, we reconstruct the mass matrix of the heavy right-handed neutrinos Ni. We analyze how the data on neutrino oscillations affect the structure of this matrix. Under the assumption of hierarchical Dirac-type neutrino masses mDi, we compute the mixing angles among Ni, their masses Mi and the lepton asymmetries εi generated in their decays. Unless special cancellations take place, one finds Mi∝ mDi2 and the generated baryon-to-photon ratio ηB is much smaller than the observed value. We show that successful baryogenesis via leptogenesis occurs in a unique special case, which corresponds to mass degeneracy and maximal mixing of N1 and N2.