Leptogenesis bound on neutrino masses in left-right symmetric models with spontaneous D-parity violation

We study the baryogenesis via leptogenesis in a class of left-right symmetric models, in which $D$-parity is broken spontaneously. We first discuss the consequence of the spontaneous $D$-parity breaking on the neutrino masses. Than we study the lepton asymmetry in various cases, from the decay of right handed neutrino as well as the triplet Higgs, depending on their relative masses they acquire from the symmetry breaking pattern. The leptogenesis bound on their masses are discussed by taking into account the low energy neutrino oscillation data. It is shown that a TeV scale leptogenesis is viable if there are additional sources of CP violation like domain wall originating from the spontaneous $D$-parity violation.Comment: 32 pages (revtex), 12 eps figures, clarifications are added in section VII, A new section VIII is added, useful references are added. Journal version, To appear in Phys. Rev.

Possible textures of the fermion mass matrices

Texture specific fermion mass matrices have played an important role in understanding several features of fermion masses and mixings. In the present work, we have given an overview of all possible cases of Fritzsch-like as well as non Fritzsch-like texture 6 and 5 zero fermion mass matrices. Further, for the case of texture 4 zero Fritzsch-like quark mass matrices, the issue of the hierarchy of the elements of the mass matrices and the role of their phases have been discussed. Furthermore, the case of texture 4 zero Fritzsch-like lepton mass matrices has also been discussed with an emphasis on the hierarchy of neutrino masses for both Majorana and Dirac neutrinos.Comment: 21 pages, 3 figure

Neutrino-Mass Hierarchies and Non-linear Representation of Lepton-Flavour Symmetry

Lepton-flavour symmetry in the Standard Model is broken by small masses for charged leptons and neutrinos. Introducing neutrino masses via dimension-5 operators associated to lepton-number violation at a very high scale, the corresponding coupling matrix may still have entries of order 1, resembling the situation in the quark sector with large top Yukawa coupling. As we have shown recently, in such a situation one may introduce the coupling matrices between lepton and Higgs fields as non-linear representations of lepton-flavour symmetry within an effective-theory framework. This allows us to separate the effects related to the large mass difference observed in atmospheric neutrino oscillations from those related to the solar mass difference. We discuss the cases of normal or inverted hierarchical and almost degenerate neutrino spectrum, give some examples to illustrate minimal lepton-flavour violation in radiative and leptonic decays, and also provide a systematic definition of next-to-minimal lepton-flavour violation within the non-linear framework.Comment: 17 pages, 1 figur

Supersymmetric Jarlskog Invariants: the Neutrino Sector

We generalize the notion of the Jarlskog invariant to supersymmetric models with right--handed neutrinos. This allows us to formulate basis--independent necessary and sufficient conditions for CP conservation in such models.Comment: 10 pages, no figure

Hierarchical neutrino masses and mixing in non minimal-SU(5)

We consider the problem of neutrino masses and mixing within the framework of a non-minimal supersymmetric SU(5) model extended by adding a set of 1,24 chiral superfields accommodating three right-handed neutrinos. A Type I+III see-saw mechanism can then be realized giving rise to a hierarchical mass spectrum for the light neutrinos of the form m_3> m_2>> m_1 consistent with present data. The extra colored states are pushed to the unification scale by proton stability constraints, while the intermediate see-saw energy scale and the unification scale are maintained in phenomenologically acceptable ranges. We also examine the issue of large neutrino mixing hierarchy \theta_{23}> \theta_{12}>> \theta_{13} in the above framework of hierarchical neutrino masses.Comment: 12 pages, 1 figure, 1 table. Captions inserted, 2 sentences for clarification added, 2 references adde

Unitarity violation in sequential neutrino mixing in a model of extra dimensions

We investigate the possibility of unitarity violation in the sequential neutrino mixing matrix in a scenario with extra compact spacelike dimensions. Gauge singlet neutrinos are assumed to propagate in one extra dimension, giving rise to an infinite tower of states in the effective four-dimensional theory. It is shown that this leads to small lepton-number violating entries in the neutrino mass matrix, which can violate unitarity on the order of one per cent.Comment: 16 pages, 2 table

Neutrinoless double beta decay and neutrino mass hierarchies

In the framework of the see-saw mechanism the normal hierarchy is favorable for the neutrino mass spectrum. For this spectrum we present a detailed calculation of the half-lives of neutrinoless double beta decay for several nuclei of experimental interest. The half-lives are evaluated by considering the most comprehensive nuclear matrix elements, which were obtained within the renormalized QRPA by the Bratislava-Caltech-Tuebingen group. The dependence of the half-lives on sin^2 theta_{13}$ and the lightest neutrino mass is studied. We present also the results of the calculations of the half-lives of neutrinoless double beta decay in the case of the inverted hierarchy of neutrino masses.Comment: 13 pages, 3 figure

Non-thermal leptogenesis with strongly hierarchical right handed neutrinos

Assuming the Dirac-type neutrino masses m_D are related to quark or charged lepton masses, neutrino oscillation data indicate that right handed neutrino masses are in general strongly hierarchical. In particular, if m_D is similar to the up-type quark masses, the mass of the lightest right handed neutrino M_1<~10^6 GeV. We show that non-thermal leptogenesis by inflaton decay can yield sufficient baryon asymmetry despite this constraint, and discuss how the asymmetry is correlated with the low energy neutrino masses and CP-violating phases.Comment: 7 pages, 5 figures. v2: added some comments and references, v3: minor corrections and additions, v4: a typo corrected, published versio

Lepton flavour violation in The Little Higgs model

Little Higgs models with T-parity have a new source of lepton flavour violation. In this paper we consider the anomalous magnetic moment of the muon \gmtwo and the lepton flavour violating decays \mutoeg and \tautomug in Little Higgs model with T-parity \cite{Goyal:2006vq}. Our results shows that present experimental constraints of \mutoeg is much more useful to constrain the new sources of flavour violation which are present in T-parity models.Comment: LaTeX file with 13 eps figures (included

Neutrinoless double-beta decay. A brief review

In this brief review we discuss the generation of Majorana neutrino masses through the see-saw mechanism, the theory of neutrinoless double-beta decay, the implications of neutrino oscillation data for the effective Majorana mass, taking into account the recent Daya Bay measurement of theta_13, and the interpretation of the results of neutrinoless double-beta decay experiments.Comment: 22 page