NEUTRINO MIXING, LEPTONIC CP VIOLATION, THE SEESAW MECHANISM AND BEYOND

2010 ◽  
Vol 25 (23) ◽  
pp. 4325-4337 ◽  
Author(s):  
S. T. PETCOV

The phenomenology of 3-neutrino mixing and of the related Dirac and Majorana leptonic CP violation is reviewed. The leptogenesis scenario of generation of the baryon asymmetry of the Universe, which is based on the see-saw mechanism of neutrino mass generation, is considered. The results showing that the CP violation necessary for the generation of the baryon asymmetry of the Universe in leptogenesis can be due exclusively to the Dirac and/or Majorana CP-violating phase(s) in the neutrino mixing matrix U are briefly reviewed.

2014 ◽  
Vol 29 (11n12) ◽  
pp. 1430028 ◽  
Author(s):  
S. T. Petcov

The phenomenology of 3-neutrino mixing, the current status of our knowledge about the 3-neutrino mixing parameters, including the absolute neutrino mass scale, and of the Dirac and Majorana CP violation in the lepton sector, are reviewed. The problems of CP violation in neutrino oscillations and of determining the nature — Dirac or Majorana — of massive neutrinos, are discussed. The seesaw mechanism of neutrino mass generation and the related leptogenesis scenario of generation of the baryon asymmetry of the universe, are considered. The results showing that the CP violation necessary for the generation of the baryon asymmetry of the universe in leptogenesis can be due exclusively to the Dirac and/or Majorana CP-violating phase(s) in the neutrino mixing matrix U, are briefly reviewed.


2015 ◽  
Vol 30 (09) ◽  
pp. 1550045 ◽  
Author(s):  
Rupam Kalita ◽  
Debasish Borah

We study the possibility of connecting leptonic Dirac CP phase δ, lightest neutrino mass and baryon asymmetry of the universe within the framework of a model where both type I and type II seesaw mechanisms contribute to neutrino mass. Type I seesaw gives rise to Tri-Bimaximal (TBM) type neutrino mixing whereas type II seesaw acts as a correction in order to generate nonzero θ13. We derive the most general form of type II seesaw mass matrix which cannot only give rise to correct neutrino mixing angles but also can generate nontrivial value of δ. Considering both the cases where type II seesaw is subleading and is equally dominant compared to type I seesaw, we correlate the type II seesaw term with δ and lightest neutrino mass. We further constrain the Dirac CP phase δ and hence the type II seesaw mass matrix from the requirement of producing the observed baryon asymmetry through the mechanism of leptogenesis.


2005 ◽  
Vol 20 (07) ◽  
pp. 477-490 ◽  
Author(s):  
SILVIA PASCOLI

Within the context of the seesaw mechanism, we review the possible connection between the CP-violating phases which appear in the lepton unitary mixing matrix and are measurable in neutrino oscillations and other low-energy processes, with the ones which play a role in the generation of the baryon asymmetry of the universe through the leptogenesis mechanism.


2019 ◽  
Vol 34 (08) ◽  
pp. 1950047
Author(s):  
Marco Chianese ◽  
Damiano F. G. Fiorillo ◽  
Gennaro Miele ◽  
Stefano Morisi

One of the main purposes of SHiP experiment is to shed light on neutrino mass generation mechanisms like the so-called seesaw. We consider a minimal type-I seesaw neutrino mass mechanism model with two heavy neutral leptons (right-handed or sterile neutrinos) with arbitrary masses. Extremely high active-sterile mixing angle requires a correlation between the phases of the Dirac neutrino couplings. Actual experimental limits on the half-life of neutrinoless double beta decay [Formula: see text]-rate on the active-sterile mixing angle are not significative in constraining the masses or the mixing measurable by SHiP.


2013 ◽  
Vol 2013 ◽  
pp. 1-20 ◽  
Author(s):  
S. T. Petcov

The compelling experimental evidences for oscillations of solar, reactor, atmospheric, and accelerator neutrinos imply the existence of 3-neutrino mixing in the weak charged lepton current. The current data on the 3-neutrino mixing parameters are summarised and the phenomenology of 3-νmixing is reviewed. The properties of massive Majorana neutrinos and of their various possible couplings are discussed in detail. Two models of neutrino mass generation with massive Majorana neutrinos—the type I see-saw and the Higgs triplet model—are briefly reviewed. The problem of determining the nature, Dirac or Majorana, of massive neutrinos is considered. The predictions for the effective Majorana mass|〈m〉|in neutrinoless double-beta-((ββ)0ν-) decay in the case of 3-neutrino mixing and massive Majorana neutrinos are summarised. The physics potential of the experiments, searching for(ββ)0ν-decay for providing information on the type of the neutrino mass spectrum, on the absolute scale of neutrino masses, and on the Majorana CP-violation phases in the PMNS neutrino mixing matrix, is also briefly discussed. The opened questions and the main goals of future research in the field of neutrino physics are outlined.


2016 ◽  
Vol 31 (09) ◽  
pp. 1650039 ◽  
Author(s):  
V. V. Vien

We study a neutrino mass model based on [Formula: see text] flavor symmetry which accommodates lepton mass, mixing with nonzero [Formula: see text] and CP violation phase. The spontaneous symmetry breaking in the model is imposed to obtain the realistic neutrino mass and mixing pattern at the tree-level with renormalizable interactions. Indeed, the neutrinos get small masses from one [Formula: see text] doublet and two [Formula: see text] singlets in which one being in [Formula: see text] and the two others in [Formula: see text] under [Formula: see text] with both the breakings [Formula: see text] and [Formula: see text] are taken place in charged lepton sector and [Formula: see text] in neutrino sector. The model also gives a remarkable prediction of Dirac CP violation [Formula: see text] or [Formula: see text] in both the normal and inverted spectrum which is still missing in the neutrino mixing matrix. The relation between lepton mixing angles is also represented.


Author(s):  
Chitta Ranjan Das ◽  
Katri Huitu ◽  
Zhanibek Kurmanaliyev ◽  
Bakytbek Mauyey ◽  
Timo Kärkkäinen

The crucial phenomenological and experimental predictions for new physics are outlined, where the number of problems of the Standard Model (neutrino masses and oscillations, dark matter, baryon asymmetry of the Universe, leptonic CP-violation) could find their solutions. The analogies between the cosmological neutrino mass scale from the early universe data and laboratory probes are discussed and the search for new physics and phenomena.


2013 ◽  
Vol 28 (29) ◽  
pp. 1350157 ◽  
Author(s):  
YONI BENTOV ◽  
A. ZEE

In the spirit of a previous study of the tetrahedral group T ≃A4, we discuss a minimalist scheme to derive the neutrino mixing matrix using the double tetrahedral group T′, the double cover of T. The new features are three distinct two-dimensional representations and complex Clebsch–Gordan coefficients, which can result in a geometric source of CP violation in the neutrino mass matrix. In an appendix, we derive explicitly the relevant group theory for the tetrahedral group T and its double cover T′.


2005 ◽  
Vol 20 (06) ◽  
pp. 1221-1233
Author(s):  
STUART RABY

In this talk I describe a natural framework for bi-large neutrino mixing within the context of two models – 1) a simple generalization of the MSSM and 2) an SO (10) model. Our starting point is the Frampton, Glashow, Yanagida [FGY] neutrino mass ansatz which can easily accomodate bi-large neutrino mixing. The main point of FGY, however, is to obtain a theory of neutrino masses with only one possible CP violating angle. They argue that the sign of the baryon asymmetry of the universe (assuming leptogenesis) is then correlated with CP asymmetries possibly observable in accelerator experiments. Unfortunately, there is a fly in the ointment. It was later shown by Raidal and Strumia [RS] that there is a sign ambiguity which frustrates the above correlation. We note that the Raidal-Strumia ambiguity is resolved in our models.


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