scholarly journals SU(5)×U(1)′ Models with a Vector-Like Fermion Family

Universe ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 356
Author(s):  
A. Karozas ◽  
G. K. Leontaris ◽  
I. Tavellaris
Keyword(s):  
B Meson ◽  
Low Energy ◽  
Fermion Mass ◽  
Anomaly Cancellation ◽  
Covering Group ◽  
Geometric Singularity ◽  
Mass Matrices ◽  
The Standard Model ◽  
Model Predictions

Motivated by experimental measurements indicating deviations from the Standard Model predictions, we discuss F-theory-inspired models, which, in addition to the three chiral generations, contain a vector-like complete fermion family. The analysis takes place in the context of $SU(5)\times U(1)'$ GUT embedded in an $E_8$ covering group, which is associated with the (highest) geometric singularity of the elliptic fibration. In this context, the $U(1)'$ is a linear combination of four abelian factors subjected to the appropriate anomaly cancellation conditions. Furthermore, we require universal $U(1)'$ charges for the three chiral families and different ones for the corresponding fields of the vector-like representations. Under the aforementioned assumptions, we find 192 models that can be classified into five distinct categories with respect to their specific GUT properties. We exhibit representative examples for each such class and construct the superpotential couplings and the fermion mass matrices. We explore the implications of the vector-like states in low-energy phenomenology, including the predictions regarding the B-meson anomalies. The rôle of R-parity violating terms appearing in some particular models of the above construction is also discussed.

scholarly journals η′K PUZZLE OF B MESON DECAYS AND NEW PHYSICS EFFECTS IN THE TC2 MODEL

2001 ◽  
Vol 16 (07) ◽  
pp. 441-455 ◽  
Author(s):  
ZHENJUN XIAO ◽  
WENJUN LI ◽  
GONGRU LU ◽  
LIBO GUO
Keyword(s):  
Standard Model ◽  
B Meson ◽  
New Physics ◽  
Decay Rates ◽  
Low Energy ◽  
Effective Hamiltonian ◽  
B Meson Decays ◽  
The Standard Model ◽  
Model Predictions ◽  
Input Parameters

Using the low energy effective Hamiltonian with the generalized factorization, we calculate the new physics contributions to B→π+π-, Kπ and Kη′ in the topcolor-assisted-technicolor (TC2) model, and compare the results with the available data. By using [Formula: see text] preferred by the CLEO data of B→π+π-decay, we find that the new physics enhancements to B→ Kη′ decays are significant in size, ~ 50% with respect to the standard model predictions, insensitive to the variations of input parameters and hence provide a simple and plausible new physics interpretation for the observed unexpectedly large B→ Kη′ decay rates.

scholarly journals The framed Standard Model (II) — A first test against experiment

2015 ◽  
Vol 30 (30) ◽  
pp. 1530060
Author(s):  
Hong-Mo Chan ◽  
Sheung Tsun Tsou
Keyword(s):  
Standard Model ◽  
Renormalization Group Equation ◽  
Fermion Mass ◽  
Group Equation ◽  
Unknown Parameters ◽  
Mass Matrices ◽  
The Standard Model ◽  
Experimental Values ◽  
The Masses ◽  
Independent Parameters

Apart from the qualitative features described in Paper I (Ref. 1), the renormalization group equation derived for the rotation of the fermion mass matrices are amenable to quantitative study. The equation depends on a coupling and a fudge factor and, on integration, on 3 integration constants. Its application to data analysis, however, requires the input from experiment of the heaviest generation masses [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] all of which are known, except for [Formula: see text]. Together then with the theta-angle in the QCD action, there are in all 7 real unknown parameters. Determining these 7 parameters by fitting to the experimental values of the masses [Formula: see text], [Formula: see text], [Formula: see text], the CKM elements [Formula: see text], [Formula: see text], and the neutrino oscillation angle [Formula: see text], one can then calculate and compare with experiment the following 12 other quantities [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and the results all agree reasonably well with data, often to within the stringent experimental error now achieved. Counting the predictions not yet measured by experiment, this means that 17 independent parameters of the standard model are now replaced by 7 in the FSM.

scholarly journals Implications of the Muon g-2 result on the flavour structure of the lepton mass matrix

2021 ◽  
Vol 81 (10) ◽  
Author(s):  
Lorenzo Calibbi ◽  
M. L. López-Ibáñez ◽  
Aurora Melis ◽  
Oscar Vives
Keyword(s):  
Mass Matrix ◽  
New Physics ◽  
Flavor Symmetry ◽  
Moment Matrix ◽  
Leptonic Sector ◽  
Mass Matrices ◽  
The Standard Model ◽  
Model Predictions ◽  
Low Energies ◽  
Lepton Flavour

AbstractThe confirmation of the discrepancy with the Standard Model predictions in the anomalous magnetic moment by the Muon g-2 experiment at Fermilab points to a low scale of new physics. Flavour symmetries broken at low energies can account for this discrepancy but these models are much more restricted, as they would also generate off-diagonal entries in the dipole moment matrix. Therefore, if we assume that the observed discrepancy in the muon $$g-2$$ g - 2 is explained by the contributions of a low-energy flavor symmetry, lepton flavour violating processes can constrain the structure of the lepton mass matrices and therefore the flavour symmetries themselves predicting these structures. We apply these ideas to several discrete flavour symmetries popular in the leptonic sector, such as $$\Delta (27)$$ Δ ( 27 ) , $$A_4$$ A 4 , and $$A_5 < imes \mathrm{CP}$$ A 5 ⋉ CP .

A DETAILED ACCOUNT OF ALAIN CONNES' VERSION OF THE STANDARD MODEL IN NON-COMMUTATIVE GEOMETRY: I AND II.

1993 ◽  
Vol 05 (03) ◽  
pp. 477-532 ◽  
Author(s):  
DANIEL KASTLER
Keyword(s):  
Standard Model ◽  
Coupling Constants ◽  
Fermion Mass ◽  
Detailed Calculation ◽  
Coupling Constant ◽  
Electroweak Interactions ◽  
Symmetrical Form ◽  
Mass Matrices ◽  
The Standard Model ◽  
Universal Coupling

We present a detailed calculation of the Lagrangian of the standard model prescribed in the paper [4] of Connes and Lott, first for the electroweak interactions alone, and then (as is necessary to achieve the correct weak hypercharge assignments) for the coupling of electroweak interactions with chromodynamics. In its most symmetrical form (with free parameters the fermion mass-matrices plus one universal coupling constant), the Connes theory in tree-approximation yields equality of the strong and electroweak coupling constants, and fixes the value sin 2 θw = 3/8, and the ratios mt/mw and mH/mt.

scholarly journals GAUGING THE SHADOW SECTOR WITH SO(3)

2000 ◽  
Vol 15 (19) ◽  
pp. 1221-1225 ◽  
Author(s):  
G. B. TUPPER ◽  
R. J. LINDEBAUM ◽  
R. D. VIOLLIER
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Gauge Group ◽  
Cold Dark Matter ◽  
Atmospheric Neutrino ◽  
Dark Matter Particle ◽  
Low Energy ◽  
Model Based ◽  
The Standard Model

We examine the phenomenology of a low-energy extension of the Standard Model, based on the gauge group SU (3) ⊗ SU (2) ⊗ U (1)⊗ SO (3), with SO(3) operating in the shadow sector. This model offers vacuum νe → νs and νμ → ντ oscillations as the solution of the solar and atmospheric neutrino problems, and it provides a neutral heavy shadow lepton X that takes the role of a cold dark matter particle.

scholarly journals APPROXIMATE FLAVOR SYMMETRIES AT A GRAND UNIFICATION SCALE

1996 ◽  
Vol 11 (12) ◽  
pp. 965-971
Author(s):  
D. GÓMEZ DUMM
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
Grand Unification ◽  
Fermion Mass ◽  
Flavor Symmetries ◽  
Mass Matrices ◽  
The Standard Model ◽  
The Hierarchical Structure ◽  
Doublet Model ◽  
Two Higgs Doublet Model

We study the evolution of fermion mass matrices considering the hypothesis of approximate flavor symmetries (AFS) in the standard model and a two-Higgs-doublet model. We find that the hierarchical structure is not significantly altered by the running, hence the assumption of AFS is entirely compatible with a grand unification scenario.

scholarly journals B decay anomalies at LHCb

2018 ◽  
Vol 175 ◽  
pp. 01004
Author(s):  
Arantza Oyanguren
Keyword(s):  
Standard Model ◽  
B Meson ◽  
Neutral Current ◽  
New Physics ◽  
Lhcb Collaboration ◽  
Beyond The Standard Model ◽  
Clear Tendency ◽  
The Standard Model ◽  
Model Predictions ◽  
Lepton Flavour

The LHCb collaboration has provided a plethora of precise measurements of flavour observables in the last years. In the B meson sector some of these results show consistent deviations from Standard Model predictions with a clear tendency to specific New Physics scenarios. B decay anomalies are found in particular related to lepton flavour universality tests and angular observables in Flavour-Changing-Neutral-Current transitions. I review here the LHCb measurements and their experimental caveats. Results from Lattice are crucial in the coming years to verify if these anomalies are explained by QCD effects or if they are unambiguous hints of physics beyond the Standard Model.

scholarly journals MASS GENERATION AND THE DYNAMICAL ROLE OF THE KATOPTRON GROUP

2001 ◽  
Vol 16 (02) ◽  
pp. 53-61 ◽  
Author(s):  
GEORGE TRIANTAPHYLLOU
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Higgs Sector ◽  
Viable Alternative ◽  
Fermion Mass ◽  
Main Function ◽  
Mass Generation ◽  
The Standard Model ◽  
Gauge Interaction

Heavy mirror fermions along with a new strong gauge interaction capable of breaking the electroweak gauge symmetry dynamically were recently introduced under the name of katoptrons. Their main function is to provide a viable alternative to the Standard-Model Higgs sector. In such a framework, ordinary fermions acquire masses after the breaking of the strong katoptron group which allows mixing with their katoptron partners. The purpose of this letter is to study the elementary-scalars-free mechanism responsible for this breaking and its implications for the fermion mass hierarchies.

scholarly journals LOW ENERGY GAUGE UNIFICATION THEORY

2002 ◽  
Vol 17 (36) ◽  
pp. 2393-2407 ◽  
Author(s):  
TIANJUN LI ◽  
WEI LIAO
Keyword(s):  
Planck Scale ◽  
Low Energy ◽  
High Dimensional ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Unified Theory ◽  
Grand Unified Theory ◽  
Anomaly Cancellation ◽  
Unification Theory ◽  
Charge Quantization

Because of the problems arising from the fermion unification in the traditional grand unified theory and the mass hierarchy between the four-dimensional Planck scale and weak scale, we suggest the low energy gauge unification theory with low high-dimensional Planck scale. We discuss the nonsupersymmetric SU(5) model on M4 × S1/Z2 × S1/Z2 and the supersymmetric SU(5) model on M4 × S1/(Z2 × Z2′) × S1/(Z2 × Z2′). The SU(5) gauge symmetry is broken by the orbifold projection for the zero modes, and the gauge unification is accelerated due to the SU(5) asymmetric light KK states. In our models, we forbid the proton decay, still keep the charge quantization, and automatically solve the fermion mass problem. We also comment on the anomaly cancellation and other possible scenarios for low energy gauge unification.

scholarly journals POSSIBLE TEXTURES OF THE FERMION MASS MATRICES

2011 ◽  
Vol 26 (18) ◽  
pp. 2973-2995 ◽  
Author(s):  
MANMOHAN GUPTA ◽  
GULSHEEN AHUJA
Keyword(s):  
Quark Mass ◽  
Fermion Mass ◽  
Neutrino Masses ◽  
Fermion Masses ◽  
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.

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