scholarly journals LOW-ENERGY SECTOR OF EIGHT-DIMENSIONAL GENERAL RELATIVITY: ELECTROWEAK MODEL AND NEUTRINO MASS

2008 ◽  
Vol 17 (05) ◽  
pp. 785-798 ◽  
Author(s):  
FRANCESCO CIANFRANI ◽  
GIOVANNI MONTANI
Keyword(s):  
General Relativity ◽  
Lower Bound ◽  
Electric Charge ◽  
Dimensional Reduction ◽  
Higgs Sector ◽  
Low Energy ◽  
Fine Tuning ◽  
Neutrino Masses ◽  
Electroweak Model ◽  
Kaluza Klein

We demonstrate that in a Kaluza–Klein space–time V4 ⊗ S1 ⊗ S3, the dimensional reduction of spinors provides a 4-field, whose associated SU(2) gauge connections are geometrized. However, additional and gauge-violating terms arise, but they are highly suppressed by a factor β, which fixes the amount of the spinor dependence on extra-coordinates. The application of this framework to the Electroweak Model is performed, thus giving a lower bound for β due to electric charge conservation. We emphasize that the Higgs sector can be reproduced also, but neutrino masses are predicted and the fine-tuning on the Higgs parameters can additionally be explained.

scholarly journals KALUZA–KLEIN DIMENSIONAL REDUCTION AND GAUSS–CODAZZI–RICCI EQUATIONS

2009 ◽  
Vol 24 (06) ◽  
pp. 1207-1220
Author(s):  
PEI WANG
Keyword(s):  
General Relativity ◽  
Dimensional Reduction ◽  
Traditional Method ◽  
Isometry Group ◽  
Extrinsic Curvature ◽  
Internal Space ◽  
Geometric Meaning ◽  
Reduced Dimensions ◽  
Lower Dimensional ◽  
Kaluza Klein

In this paper we imitate the traditional method which is used customarily in the general relativity and some mathematical literatures to derive the Gauss–Codazzi–Ricci equations for dimensional reduction. It would be more distinct concerning geometric meaning than the vielbein method. Especially, if the lower-dimensional metric is independent of reduced dimensions the counterpart of the symmetric extrinsic curvature is proportional to the antisymmetric Kaluza–Klein gauge field strength. For isometry group of internal space, the SO (n) symmetry and SU (n) symmetry are discussed. And the Kaluza–Klein instanton is also enquired.

scholarly journals A FRAMEWORK TO SIMULTANEOUSLY EXPLAIN TINY NEUTRINO MASS AND HUGE MISSING MASS PROBLEM OF THE UNIVERSE

2010 ◽  
Vol 25 (25) ◽  
pp. 2111-2120 ◽  
Author(s):  
YASAMAN FARZAN
Keyword(s):  
Dark Matter ◽  
Lower Bound ◽  
Neutrino Mass ◽  
Upper Bound ◽  
Low Energy ◽  
Neutrino Masses ◽  
Energy Scenario ◽  
The Masses ◽  
The Universe

A minimalistic scenario is developed to explain dark matter and tiny but nonzero neutrino masses. A new scalar called SLIM plays the role of the dark matter. Neutrinos achieve Majorana mass through a one-loop diagram. This scenario can be realized for both real and complex SLIM. Simultaneously explaining the neutrino mass and dark matter abundance constrains the scenario. In particular for real SLIM, an upper bound of a few MeV on the masses of the new particles and a lower bound on their coupling is obtained which make the scenario testable. The low energy scenario can be embedded within various SU (2)× U (1) symmetric models. A specific example is introduced and its phenomenological consequences are discussed.

scholarly journals Neutrino Mass, Coupling Unification, Verifiable Proton Decay, Vacuum Stability, and WIMP Dark Matter in SU(5)

2018 ◽  
Vol 2018 ◽  
pp. 1-21 ◽  
Author(s):  
Biswonath Sahoo ◽  
Mainak Chakraborty ◽  
M. K. Parida
Keyword(s):  
Dark Matter ◽  
Lower Bound ◽  
Scalar Potential ◽  
Higgs Sector ◽  
Threshold Effect ◽  
Neutrino Masses ◽  
Vacuum Stability ◽  
Stability Issue ◽  
Proton Lifetime ◽  
Gauge Couplings

Nonsupersymmetric minimal SU(5) with Higgs representations 24H and 5H and standard fermions in 5¯F⊕10F is well known for its failure in unification of gauge couplings and lack of predicting neutrino masses. Like standard model, it is also affected by the instability of the Higgs scalar potential. We note that extending the Higgs sector by 75H and 15H not only leads to the popular type-II seesaw ansatz for neutrino masses with a lower bound on the triplet mass MΔ>2×109 GeV, but also achieves precision unification of gauge couplings without proliferation of nonstandard light Higgs scalars or fermions near the TeV scale. Consistent with recent LUX-2016 lower bound, the model easily accommodates a singlet scalar WIMP dark matter near the TeV scale which resolves the vacuum stability issue even after inclusion of heavy triplet threshold effect. We estimate proton lifetime predictions for p→e+π0 including uncertainties due to input parameters and threshold effects due to superheavy Higgs scalars and superheavy X±4/3,Y±1/3 gauge bosons. The predicted lifetime is noted to be verifiable at Super Kamiokande and Hyper Kamiokande experiments.

scholarly journals The Swampland Conjectures: A Bridge from Quantum Gravity to Particle Physics

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 273
Author(s):  
Mariana Graña ◽  
Alvaro Herráez
Keyword(s):  
Effective Field Theories ◽  
Quantum Gravity ◽  
Particle Physics ◽  
Effective Field ◽  
Low Energy ◽  
Field Theories ◽  
Neutrino Masses ◽  
Higgs Potential ◽  
Photon Mass ◽  
Effective Theories

The swampland is the set of seemingly consistent low-energy effective field theories that cannot be consistently coupled to quantum gravity. In this review we cover some of the conjectural properties that effective theories should possess in order not to fall in the swampland, and we give an overview of their main applications to particle physics. The latter include predictions on neutrino masses, bounds on the cosmological constant, the electroweak and QCD scales, the photon mass, the Higgs potential and some insights about supersymmetry.

scholarly journals ON THE KALUZA–KLEIN GEOMETRIZATION OF THE ELECTROWEAK MODEL WITHIN A GAUGE THEORY OF THE FIVE-DIMENSIONAL LORENTZ GROUP

2006 ◽  
Vol 15 (05) ◽  
pp. 717-736
Author(s):  
ORCHIDEA MARIA LECIAN ◽  
GIOVANNI MONTANI
Keyword(s):  
Gauge Theory ◽  
Lorentz Group ◽  
Lagrangian Density ◽  
Gauge Fields ◽  
Normalization Factor ◽  
Current Term ◽  
Electroweak Model ◽  
Kaluza Klein

The geometrization of the Electroweak Model is achieved in a five-dimensional Riemann–Cartan framework. Matter spinorial fields are extended to 5 dimensions by the choice of a proper dependence on the extracoordinate and of a normalization factor. U (1) weak hypercharge gauge fields are obtained from a Kaluza–Klein scheme, while the tetradic projections of the extradimensional contortion fields are interpreted as SU (2) weak isospin gauge fields. SU (2) generators are derived by the identification of the weak isospin current to the extradimensional current term in the Lagrangian density of the local Lorentz group. The geometrized U (1) and SU (2) groups will provide the proper transformation laws for bosonic and spinorial fields. Spin connections will be found to be purely Riemannian.

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 Higgs sector and fine-tuning in the phenomenological MSSM

2012 ◽  
Vol 86 (7) ◽  
Author(s):  
Matthew W. Cahill-Rowley ◽  
JoAnne L. Hewett ◽  
Ahmed Ismail ◽  
Thomas G. Rizzo
Keyword(s):  
Higgs Sector ◽  
Fine Tuning

scholarly journals THE GRACEFUL EXIT FROM THE ANOMALY-INDUCED INFLATION: SUPERSYMMETRY AS A KEY

2002 ◽  
Vol 11 (08) ◽  
pp. 1159-1169 ◽  
Author(s):  
I. L. SHAPIRO
Keyword(s):  
Supersymmetry Breaking ◽  
Low Energy ◽  
Fine Tuning ◽  
Starobinsky Model ◽  
Expansion Of The Universe ◽  
Soft Supersymmetry Breaking ◽  
The Universe

The stable version of the anomaly-induced inflation does not need a fine tuning to induce sufficient expansion of the Universe. The non-stable version (Starobinsky model) provides the graceful exit to the FRW phase. Here, we indicate the possibility of the inflation which is stable at the beginning and unstable at the end. The effect is due to the soft supersymmetry breaking and the decoupling of the massive sparticles at low energy.

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