Flavored leptogenesis with quasidegenerate neutrinos in a broken cyclic symmetric model

Cyclic symmetry in the neutrino sector with the type-I seesaw mechanism in the mass basis of charged leptons and right chiral neutrinos (N-iR, i = e, mu, tau) generates a twofold degenerate light neutrino and a threefold degenerate heavy neutrino mass spectrum. Consequently, such a scheme produces vanishing one light neutrino mass squared difference and lepton asymmetry. To circumvent such an unphysical outcome, we break cyclic symmetry in the diagonal right chiral neutrino mass term by a small breaking parameter. Nonzero mass squared differences and mixing angles are generated with the help of the small breaking parameter. The smallness of the breaking parameter opens up the possibility of resonant leptogenesis. Assuming complex Yukawa couplings, we derive generalized expressions with flavor-dependent CP asymmetry parameters (epsilon(alpha)(i)) which are valid for the quasidegenerate as well as hierarchical mass spectrum of right-handed neutrinos. Thereafter, we set up the chain of coupled Boltzmann equations (which are flavor dependent too) which have to be solved in order to get the final lepton asymmetries. Depending upon the temperature regime, the CP asymmetries and the Boltzmann equations may also be flavor independent. As our goal is to study the enhancement of CP asymmetry due to the quasidegeneracy of right-handed neutrinos, we select only the lowest allowed (by neutrino oscillation data) value of the breaking parameter (and other corresponding Lagrangian parameters) and estimate the baryon asymmetry parameter Y-B. The experimental constraint of Y-B introduces a bound on right-handed neutrino mass which remained unrestricted by neutrino oscillation data.