scholarly journals THE PROBLEM OF NEUTRINO MASSES IN EXTENSIONS OF THE STANDARD MODEL

2001 ◽  
Vol 16 (32) ◽  
pp. 5101-5199 ◽  
Author(s):  
ISABELLA MASINA
Keyword(s):  
Proton Decay ◽  
Fine Tuning ◽  
Neutrino Masses ◽  
Flavor Symmetry ◽  
Mixing Angle ◽  
Grand Unified Theories ◽  
Triplet Splitting ◽  
Fermion Masses ◽  
The Standard Model ◽  
Neutrino Masses And Mixings

We review the problem of neutrino masses and mixings in the context of grand unified theories. After a brief summary of the present experimental status of neutrino physics, we describe how the see-saw mechanism can automatically account for the large atmospheric mixing angle. We provide two specific examples where this possibility is realized by means of a flavor symmetry. We then review in some detail the various severe problems which plague minimal GUT models (like the doublet–triplet splitting and proton-decay) and which force us to investigate the possibility of constructing more elaborate but realistic models. We then show an example of a quasirealistic SUSY SU(5) model which, by exploiting the crucial presence of an Abelian flavor symmetry, does not require any fine-tuning and predicts a satisfactory phenomenology with respect to coupling unification, fermion masses and mixings and bounds from proton decay.

scholarly journals GAUGE BOSON FAMILIES IN GRAND UNIFIED THEORIES OF FERMION MASSES: $E_6^4 \rtimes S_4$

2007 ◽  
Vol 22 (14n15) ◽  
pp. 2469-2491 ◽  
Author(s):  
FRANCESCO CARAVAGLIOS ◽  
STEFANO MORISI
Keyword(s):  
Gauge Group ◽  
Gauge Boson ◽  
Neutrino Masses ◽  
Group Factor ◽  
Second Quantization ◽  
Gauge Bosons ◽  
Fermion Masses ◽  
The Standard Model ◽  
Electron Field ◽  
Neutrino Masses And Mixings

In third quantization the origin of fermion families is easy to understand: the electron field, the muon field and the tau field are identical fields in precisely the same sense as three electrons are identical and indistinguishable particles of a theory of second quantization. In both cases, the permutation of these fields or particles leaves the Lagrangian invariant. One can also extend the concept of family to gauge bosons. This can be obtained through the semidirect product of the gauge group with the group of permutations of n objects. In this paper we have studied the group [Formula: see text]. We explain why we have chosen E6 as fundamental gauge group factor and why we start with a model with four gauge boson/fermion families to accommodate and to fit the Standard Model with only three fermion families. We suggest a possible symmetry breaking pattern of [Formula: see text] that could explain quark, lepton and neutrino masses and mixings.

scholarly journals Baryogenesis and dark matter in U(1) extensions

2017 ◽  
Vol 32 (15) ◽  
pp. 1740005 ◽  
Author(s):  
Wan-Zhe Feng ◽  
Pran Nath
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Lepton Number ◽  
Current Data ◽  
Neutrino Masses ◽  
Neutrino Experiment ◽  
The Standard Model ◽  
Reactor Neutrino ◽  
The Universe ◽  
Neutrino Masses And Mixings

A brief review is given of some recent works where baryogenesis and dark matter have a common origin within the U(1) extensions of the Standard Model (SM) and of the minimal supersymmetric Standard Model (MSSM). The models considered generate the desired baryon asymmetry and the dark matter to baryon ratio. In one model, all of the fundamental interactions do not violate lepton number, and the total [Formula: see text] in the Universe vanishes. In addition, one may also generate a normal hierarchy of neutrino masses and mixings in conformity with the current data. Specifically, one can accommodate [Formula: see text] consistent with the data from Daya Bay reactor neutrino experiment.

Texture zero mass matrices and flavor mixing of quarks and leptons

2015 ◽  
Vol 30 (28) ◽  
pp. 1550138 ◽  
Author(s):  
Harald Fritzsch
Keyword(s):  
Experimental Data ◽  
Neutrino Masses ◽  
Mixing Angle ◽  
Mixing Angles ◽  
Zero Mass ◽  
Fermion Masses ◽  
Mass Matrices ◽  
Flavor Mixing ◽  
Texture Zero ◽  
The Masses

We discuss mass matrices with four texture zeros for the quarks and leptons. The three mixing angles for the quarks and leptons are functions of the fermion masses. The results agree with the experimental data. The ratio of the masses of the first two neutrinos is given by the solar mixing angle. The neutrino masses are calculated: [Formula: see text], [Formula: see text] and [Formula: see text].

scholarly journals MUONIUM–ANTIMUONIUM OSCILLATIONS AND MASSIVE MAJORANA NEUTRINOS

2004 ◽  
Vol 19 (04) ◽  
pp. 297-306 ◽  
Author(s):  
T. E. CLARK ◽  
S. T. LOVE
Keyword(s):  
Matrix Element ◽  
Interesting Case ◽  
Neutrino Masses ◽  
Leading Order ◽  
Seesaw Mechanism ◽  
The Standard Model ◽  
Oscillation Process ◽  
Majorana Neutrinos ◽  
Order Matrix Element ◽  
Neutrino Masses And Mixings

The electron and muon number violating muonium–antimuonium oscillation process can proceed provided that neutrinos have nonzero masses and mix among the various generations. Modifying the Standard Model only by the inclusion of singlet right-handed neutrino fields and allowing for general neutrino masses and mixings, the leading order matrix element contributing to this process is computed. For the particularly interesting case where the neutrino masses are generated by a seesaw mechanism with a very large Majorana mass MR≫MW, it is found that both the very light and very heavy Majorana neutrinos each give comparable contributions to the oscillation time scale proportional to [Formula: see text]. Present experimental limits set by the non-observation of the oscillation process sets a lower limit on MR of roughly of order 104 GeV.

scholarly journals SUPERSYMMETRY AND UNIFICATION: HEAVY TOP WAS THE KEY

2012 ◽  
Vol 13 ◽  
pp. 182-190 ◽  
Author(s):  
GORAN SENJANOVIĆ
Keyword(s):  
Top Quark ◽  
Quark Mass ◽  
Correct Prediction ◽  
Top Quark Mass ◽  
Weak Mixing Angle ◽  
Mixing Angle ◽  
Grand Unified Theories ◽  
The Standard Model ◽  
Unified Theories ◽  
History Of

I review the history of the unification of gauge couplings of the Standard Model. I start by recalling the history of the most important prediction of low-energy supersymmetry: the correct prediction of the weak mixing angle tied to the prediction of a large top quark mass. I then turn to the discussion of the present day situation of the minimal supersymmetric Grand Unified Theories based on SU(5) and SO(10) groups. For the sake of completeness I also summarize the problems and possible solution of the minimal ordinary SU(5).

scholarly journals SUPERSYMMETRIC UNIFICATION AND R SYMMETRIES

2012 ◽  
Vol 27 (40) ◽  
pp. 1230044 ◽  
Author(s):  
MU-CHUN CHEN ◽  
MAXIMILIAN FALLBACHER ◽  
MICHAEL RATZ
Keyword(s):  
Higgs Mass ◽  
Mass Term ◽  
Four Dimensions ◽  
Grand Unified Theories ◽  
Triplet Splitting ◽  
Fermion Masses ◽  
Higher Dimensional ◽  
Splitting Problem ◽  
Order Four

We review the role of R symmetries in models of supersymmetric unification in four and more dimensions, and in string theory. We show that, if one demands anomaly freedom and fermion masses, only R symmetries can forbid the supersymmetric Higgs mass term μ. We then review the proof that R symmetries are not available in conventional grand unified theories (GUTs) and argue that this prevents natural solutions to the doublet–triplet splitting problem in four dimensions. On the other hand, higher-dimensional GUTs do not suffer from this problem. We briefly comment on an explicit string-derived model in which the μ and dimension-5 proton decay problems are solved simultaneously by an order four discrete R symmetry. We also comment on the higher-dimensional origin of this symmetry.

scholarly journals Supersymmetric U(1)Y′⊗ U(1)B−L extension of the Standard Model

2017 ◽  
Vol 32 (16) ◽  
pp. 1750093 ◽  
Author(s):  
J. C. Montero ◽  
V. Pleitez ◽  
B. L. Sánchez-Vega ◽  
M. C. Rodriguez
Keyword(s):  
Gauge Symmetry ◽  
Mass Spectra ◽  
Tree Level ◽  
Neutrino Masses ◽  
Type I ◽  
Seesaw Mechanism ◽  
Active Neutrino ◽  
Supersymmetric Version ◽  
Fermion Masses ◽  
The Standard Model

We build a supersymmetric version with [Formula: see text] gauge symmetry, where [Formula: see text] is a new charge and [Formula: see text] and [Formula: see text] are the usual baryonic and leptonic numbers. The model has three right-handed neutrinos with identical [Formula: see text] charges, and can accommodate all fermion masses at the tree level. In particular, the type I seesaw mechanism is implemented for the generation of the active neutrino masses. We obtain the mass spectra of all sectors and for the scalar one we also give the flat directions allowed by the model.

scholarly journals NEUTRINO PHYSICS (THEORY)

2005 ◽  
Vol 20 (22) ◽  
pp. 5254-5265 ◽  
Author(s):  
PAUL LANGACKER
Keyword(s):  
Neutrino Physics ◽  
Standard Model ◽  
Neutrino Masses ◽  
Bottom Up ◽  
Basic Framework ◽  
The Standard Model ◽  
The Status ◽  
Neutrino Masses And Mixings

Nonzero neutrino masses are the first definitive need to extend the standard model. After reviewing the basic framework, I describe the status of some of the major issues, including tests of the basic framework of neutrino masses and mixings; the question of Majorana vs. Dirac; the spectrum, mixings, and number of neutrinos; models, with special emphasis on constraints from typical superstring constructions (which are not consistent with popular bottom-up assumptions); and other implications.

scholarly journals CP violation in the lepton sector and implications for leptogenesis

2018 ◽  
Vol 33 (05n06) ◽  
pp. 1842006 ◽  
Author(s):  
C. Hagedorn ◽  
R. N. Mohapatra ◽  
E. Molinaro ◽  
C. C. Nishi ◽  
S. T. Petcov
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Low Energy ◽  
Current Status ◽  
Neutrino Masses ◽  
Flavor Symmetry ◽  
Lepton Sector ◽  
The Standard Model ◽  
Mixing Matrix ◽  
Cp Symmetry

We review the current status of the data on neutrino masses and lepton mixing and the prospects for measuring the CP-violating phases in the lepton sector. The possible connection between low energy CP violation encoded in the Dirac and Majorana phases of the Pontecorvo–Maki–Nakagawa–Sakata mixing matrix and successful leptogenesis is emphasized in the context of seesaw extensions of the Standard Model with a flavor symmetry [Formula: see text] (and CP symmetry).

scholarly journals A NewS4Flavor Symmetry in 3-3-1 Model with Neutral Fermions

2014 ◽  
Vol 2014 ◽  
pp. 1-24 ◽  
Author(s):  
V. V. Vien ◽  
H. N. Long
Keyword(s):  
Scalar Potential ◽  
Neutrino Masses ◽  
Neutrino Mixing ◽  
Gauge Bosons ◽  
Quark Masses ◽  
Model Based ◽  
Fermion Masses ◽  
The Standard Model ◽  
Mixing Matrix ◽  
The Difference

A newS4flavor model based onSU(3)C⊗SU(3)L⊗U(1)Xgauge symmetry responsible for fermion masses and mixings is constructed. The neutrinos get small masses from only an antisextet ofSU(3)Lwhich is in a doublet underS4. In this work, we assume the VEVs of the antisextet differ from each other underS4and the difference of these VEVs is regarded as a small perturbation, and then the model can fit the experimental data on neutrino masses and mixings. Our results show that the neutrino masses are naturally small and a deviation from the tribimaximal neutrino mixing form can be realized. The quark masses and mixing matrix are also discussed. The number of required Higgs multiplets is less and the scalar potential of the model is simpler than those of the model based onS3and our previousS4model. The assignation of VEVs to antisextet leads to the mixing of the new gauge bosons and those in the standard model. The mixing in the charged gauge bosons as well as the neutral gauge bosons is considered.

Sign in / Sign up

Export Citation Format

Share Document