Flat manifold leptogenesis in the supersymmetric standard model
Flat manifold leptogenesis a la Affleck-Dine is investigated with the slepton and Higgs fields, L, H_u, H_d, in the supersymmetric standard model. The multi-dimensional motion of these scalar fields is realized in the case that the L H_u and H_u H_d directions are comparably flat with the relevant non-renormalizable superpotential terms. Soon after the inflation, the lepton number asymmetry appears to fluctuate due to this multi-dimensional motion involving certain CP violating phases. Then, it is fixed to some significant non-zero value for the successful baryogenesis when the scalar fields begin to oscillate with rotating phases driven by the quartic coupling from the superpotential term h_e L H_d e^c with h_e \sim 10^-5 - 10^-3. The Hubble parameter H_osc at this epoch for the completion of leptogenesis is much larger than the gravitino mass m_3/2 \sim 10^3 GeV. The thermal terms may even play a cooperative role in this scenario of early leptogenesis. The lightest neutrino mass can be 10^-4 eV, if the reheating temperature is allowed to be 10^10 GeV.