Related papers: Leptogenesis With Many Neutrinos
We propose a novel leptogenesis mechanism with a temperature-dependent coupling between the right-handed neutrino and Standard Model particles. This coupling experiences suppression at high temperatures and becomes sizable when the lepton…
Seesaw models with a slightly broken lepton number symmetry can explain small neutrino masses, and allow for low-scale leptogenesis. We make a thorough analysis of leptogenesis within the simplest model with two right-handed (RH) neutrinos…
In a class of two Higgs doublet model, where one Higgs doublet generates masses of quarks and charged leptons whereas the other Higgs doublet with a tiny vacuum expectation value (VEV) generates neutrino Dirac masses, smallness of neutrino…
We reanalyze the supersymmetric leptogenesis model by one of the authors (HM) and Yanagida based on \tilde{L} = H_u flat direction in detail. We point out that the appropriate amount of baryon asymmetry can be generated in this model with…
Motivated by the scenario of resonant leptogenesis in which lepton number creation in the electroweak-scale is relevant, we investigate the spectral properties and possible collective nature of the standard model neutrinos at electroweak…
In some classes of flavour models based on unified theories with a type I see-saw mechanism, the prediction for the mass of the lightest right-handed neutrino is in conflict with the lower bound from the requirement of successful thermal…
It is shown that the type III seesaw mechanism proposed recently can have certain advantages over the conventional (or type I) seesaw mechanism for leptogenesis. In particular a resonant enhancement of leptogenesis via heavy quasi-Dirac…
In a minimal model of leptogenesis, the observed baryon asymmetry is realized after high-scale reheating into the lightest sterile neutrino. We consider constraints on this scenario from the stability of the Higgs vacuum during pre-heating.…
We show that by adding to the standard model plus the type I seesaw different types of scalars, it is possible to construct models that satisfy the three requirements of (i) generating neutrino masses at the TeV scale, (ii) being testable…
We explore the hypothesis of having an approximate lepton number conservation as a way to achieve a successful leptogenesis in low-scale seesaw mechanisms. The smallness of the active neutrino masses, as well as a strong degeneracy in the…
We study a leptogenesis via decays of heavy Majorana neutrinos produced non-thermally in inflaton decays. We find that this scenario is fully consistent with existing supersymmetric inflation models such as for topological or for hybrid…
We study if leptogenesis works successfully together with the neutrino mass anarchy hypothesis. We find that the predicted neutrino mass spectrum is sensitive to the reheating temperature or the inflaton mass, while the distributions of the…
We investigate the possibility of low-scale leptogenesis in the minimal supersymmetric standard model extended with right handed (s)neutrinos. We demonstrate that successful leptogenesis can be easily achieved at a scale as low as ~ TeV…
We make a simple observation that if one of the right-chiral neutrinos is very heavy or its Yukawa couplings to the standard lepton doublets are negligible, so that it effectively decouples from the see-saw mechanism, the prediction for the…
Models with composite singlet neutrinos can give small Majorana or Dirac masses to the active neutrinos. The mechanism is based on the fact that conserved chiral symmetries give massless neutrinos at the renormalizable level. Thus, they…
We discuss leptogenesis in a majoron model extended by a right-handed $SU(2)_L$ triplet fermion. We study several different parameter assignments and find that the interactions of neutrinos with the new particles in the majoron+triplet…
We show that the reheating temperature of a matter-domination era in the early universe can be pushed down to the neutrino decoupling temperature at around $2 \ {\rm MeV}$ if the reheating takes place through non-hadronic decays of the…
We study the scenario of thermal leptogenesis in which the leptonic asymmetries are resonantly enhanced through the mixing of nearly degenerate heavy Majorana neutrinos that have mass differences comparable to their decay widths.…
In the supersymmetric triplet (type-II) seesaw model, in which a single SU(2)_L-triplet couples to leptons, the high-energy neutrino flavour structure can be directly determined from the low-energy neutrino data. We show that even with such…
We show that a phase transition may take place in the early Universe at a temperature $T_*$ via a Standard Model singlet scalar field which happens to couple to right handed neutrinos (RHN) resulting a temperature dependent mass for them…