A simple connection between neutrino oscillation and leptogenesis

The usual see-saw formula is modified by the presence of two Higgs tripletsin left-right symmetric theories. The contribution from the left-handed Higgstriplet to the see-saw formula can dominate over the conventional one when theneutrino Dirac mass matrix is identified with the charged lepton or down quarkmass matrix. In this case an analytic calculation of the lepton asymmetry,generated by the decay of the lightest right-handed Majorana neutrino, ispossible. For typical parameters, the out-of-equilibrium condition for thedecay is automatically fulfilled. The baryon asymmetry has the correct order ofmagnitude, as long as the lightest mass eigenstate is not much lighter then10^{-6} to 10^{-8} eV, depending on the solution of the solar neutrino problem.A sizable signal in neutrinoless double beta decay can be expected, as long asthe smallest mass eigenstate is not much lighter than 10^{-3} eV and the Diracmass matrix is identified with the charged lepton mass matrix.Comment: 16 pages, 3 figures. One paragraph and some references added, typos correcte