scholarly journals Has the origin of the third-family fermion masses been determined?

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Michael J. Baker ◽  
Peter Cox ◽  
Raymond R. Volkas
Keyword(s):  
Precision Measurements ◽  
Tree Level ◽  
Fermion Mass ◽  
Mass Generation ◽  
Quark Masses ◽  
The Third ◽  
Fermion Masses ◽  
The Standard Model ◽  
First Time ◽  
Rule Out

Abstract Precision measurements of the Higgs couplings are, for the first time, directly probing the mechanism of fermion mass generation. The purpose of this work is to determine to what extent these measurements can distinguish between the tree-level mechanism of the Standard Model and the theoretically motivated alternative of radiative mass generation. Focusing on the third-family, we classify the minimal one-loop models and find that they fall into two general classes. By exploring several benchmark models in detail, we demonstrate that a radiative origin for the tau-lepton and bottom-quark masses is consistent with current observations. While future colliders will not be able to rule out a radiative origin, they can probe interesting regions of parameter space.

B − L extension of the Standard Model based on Σ(18) symmetry for fermion mass and mixing

2020 ◽  
Vol 35 (27) ◽  
pp. 2050223
Author(s):  
V. V. Vien
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Neutrino Mass ◽  
Tree Level ◽  
Fermion Mass ◽  
Recent Experimental Data ◽  
Type I ◽  
Quark Masses ◽  
The Standard Model ◽  
Experimental Values

In this work, we suggest a renormalizable [Formula: see text] extension of the Standard Model with [Formula: see text] symmetry in which the observed fermion mass and mixing pattern is consistent with the experimental values given in Ref. 1 at the tree-level. The neutrino mass ordering and the tiny neutrino masses are induced by the type-I seesaw mechanism. The effective neutrino mass parameters are predicted to be [Formula: see text], [Formula: see text] for NO and [Formula: see text], [Formula: see text] for IO which are well consistent with the recent experimental data. The quark masses are in good agreement while the quark mixing matrix has a little difference with the experimental data taken from Ref. 1 and the Cabibbo angle [Formula: see text] is related to the model parameter [Formula: see text] by the formula [Formula: see text].

Fermion masses and mixings in a 3-3-1 model withQ4symmetry

2019 ◽  
Vol 34 (25) ◽  
pp. 1950198
Author(s):  
V. V. Vien ◽  
D. P. Khoi
Keyword(s):  
Neutrino Mass ◽  
Mass Parameter ◽  
Majorana Neutrino ◽  
Tree Level ◽  
Type I ◽  
Inverted Hierarchy ◽  
Quark Masses ◽  
Fermion Masses ◽  
Majorana Neutrino Mass ◽  
Good Agreement

We construct a renormalizable [Formula: see text] model with [Formula: see text] symmetry accommodating the observed pattern of fermion masses and mixings with Dirac CP violation phase. The smallness of the active neutrino masses arises from a combination of type I and type II seesaw mechanisms. Both normal and inverted neutrino mass ordering are viable in our model in which the obtained physical observables of the lepton sector are well consistent with the global fit of neutrino oscillation data [P. F. de Salas et al., Phys. Lett. B 782, 633 (2018)] while the CKM matrix is unity at tree level and the quark masses are in good agreement with the experimental data [Particle Data Group (M. Tanabashi et al.), Phys. Rev. D 98, 030001 (2018)]. Furthermore, the model also predicts an effective Majorana neutrino mass parameter of [Formula: see text] eV for normal hierarchy and [Formula: see text] for inverted hierarchy which are consistent with the constraints given in [P. F. de Salas et al., Phys. Lett. B 782, 633 (2018)].

scholarly journals Universal relations with fermionic dark matter

2018 ◽  
Vol 168 ◽  
pp. 04015
Author(s):  
A. Krut ◽  
C. R. Argüelles ◽  
J. A. Rueda ◽  
R. Ruffini
Keyword(s):  
Dark Matter ◽  
Finite Size ◽  
Elliptical Galaxies ◽  
Compact Objects ◽  
Space Distribution ◽  
Fermion Mass ◽  
Fermion Masses ◽  
Natural Mechanism ◽  
First Time ◽  
Good Agreement

We have recently introduced a new model for the distribution of dark matter (DM) in galaxies, the Ruffini-Argüelles-Rueda (RAR) model, based on a self-gravitating system of massive fermions at finite temperatures. The RAR model, for fermion masses above keV, successfully describes the DM halos in galaxies, and predicts the existence of a denser quantum core towards the center of each configuration. We demonstrate here, for the first time, that the introduction of a cutoff in the fermion phase-space distribution, necessary to account for galaxies finite size and mass, defines a new solution with a compact quantum core which represents an alternative to the central black hole (BH) scenario for SgrA*. For a fermion mass in the range 48keV ≤ mc2 ≤ 345keV, the DM halo distribution fulfills the most recent data of the Milky Way rotation curves while harbors a dense quantum core of 4×106M⊙ within the S2 star pericenter. In particular, for a fermion mass of mc2 ∼ 50keV the model is able to explain the DM halos from typical dwarf spheroidal to normal elliptical galaxies, while harboring dark and massive compact objects from ∼ 103M⊙ tp to 108M⊙ at their respective centers. The model is shown to be in good agreement with different observationally inferred universal relations, such as the ones connecting DM halos with supermassive dark central objects. Finally, the model provides a natural mechanism for the formation of supermassive BHs as heavy as few ∼ 108M⊙. We argue that larger BH masses (few ∼ 109−10M⊙) may be achieved by assuming subsequent accretion processes onto the above heavy seeds, depending on accretion efficiency and environment.

scholarly journals ANOMALOUS FERMION MASS GENERATION AT THREE LOOPS

2013 ◽  
Vol 28 (22) ◽  
pp. 1350083 ◽  
Author(s):  
APOSTOLOS PILAFTSIS
Keyword(s):  
Gauge Theory ◽  
Quantum Gravity ◽  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Model Building ◽  
Heavy Fermions ◽  
Fermion Mass ◽  
Mass Generation ◽  
Fermion Masses ◽  
Gravity Effects

We present a novel mechanism for generating fermion masses through global anomalies at the three-loop level. In a gauge theory, global anomalies are triggered by the possible existence of scalar or pseudoscalar states and heavy fermions, whose masses may not necessarily result from spontaneous symmetry breaking. The implications of this mass-generating mechanism for model building are discussed, including the possibility of creating low-scale fermion masses by quantum gravity effects.

scholarly journals Leptogenesis and fermion mass fit in a renormalizable SO(10) model

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
V. Suryanarayana Mummidi ◽  
Ketan M. Patel
Keyword(s):  
Numerical Solutions ◽  
Double Beta Decay ◽  
Fermion Mass ◽  
Strong Correlations ◽  
Yukawa Couplings ◽  
Mixing Parameters ◽  
Fermion Masses ◽  
The Standard Model ◽  
The Right ◽  
Yukawa Sector

Abstract A non-supersymmetric renormalizable SO(10) model is investigated for its viability in explaining the observed fermion masses and mixing parameters along with the baryon asymmetry produced via thermal leptogenesis. The Yukawa sector of the model consists of complex 10H and $$ {\overline{126}}_H $$ 126 ¯ H scalars with a Peccei-Quinn like symmetry and it leads to strong correlations among the Yukawa couplings of all the standard model fermions including the couplings and masses of the right-handed (RH) neutrinos. The latter implies the necessity to include the second lightest RH neutrino and flavor effects for the precision computation of leptogenesis. We use the most general density matrix equations to calculate the temperature evolution of flavoured leptonic asymmetry. A simplified analytical solution of these equations, applicable to the RH neutrino spectrum predicted in the model, is also obtained which allows one to fit the observed baryon to photon ratio along with the other fermion mass observables in a numerically efficient way. The analytical and numerical solutions are found to be in agreement within a factor of $$ \mathcal{O}(1) $$ O 1 . We find that the successful leptogenesis in this model does not prefer any particular value for leptonic Dirac and Majorana CP phases and the entire range of values of these observables is found to be consistent. The model specifically predicts (a) the lightest neutrino mass $$ {m}_{v_1} $$ m v 1 between 2–8 meV, (b) the effective mass of neutrinoless double beta decay mββ between 4–10 meV, and (c) a particular correlation between the Dirac and one of the Majorana CP phases.

scholarly journals Precision test of the muon-Higgs coupling at a high-energy muon collider

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Tao Han ◽  
Wolfgang Kilian ◽  
Nils Kreher ◽  
Yang Ma ◽  
Jürgen Reuter ◽  
...  
Keyword(s):  
Standard Model ◽  
High Energy ◽  
New Physics ◽  
Fermion Mass ◽  
Beyond The Standard Model ◽  
Higgs Coupling ◽  
Mass Generation ◽  
High Energy Muon ◽  
The Standard Model ◽  
Muon Collider

Abstract We explore the sensitivity of directly testing the muon-Higgs coupling at a high-energy muon collider. This is strongly motivated if there exists new physics that is not aligned with the Standard Model Yukawa interactions which are responsible for the fermion mass generation. We illustrate a few such examples for physics beyond the Standard Model. With the accidentally small value of the muon Yukawa coupling and its subtle role in the high-energy production of multiple (vector and Higgs) bosons, we show that it is possible to measure the muon-Higgs coupling to an accuracy of ten percent for a 10 TeV muon collider and a few percent for a 30 TeV machine by utilizing the three boson production, potentially sensitive to a new physics scale about Λ ∼ 30 − 100 TeV.

scholarly journals Fermion mass hierarchy in grand gauge-Higgs unification

2019 ◽  
Vol 2019 (8) ◽  
Author(s):  
Nobuhito Maru ◽  
Yoshiki Yatagai
Keyword(s):  
Top Quark ◽  
Electroweak Symmetry Breaking ◽  
Boson Mass ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Electroweak Symmetry ◽  
Fermion Masses ◽  
The Standard Model ◽  
Mass Terms ◽  
The One

Abstract Grand gauge-Higgs unification of 5D $SU(6)$ gauge theory on an orbifold $S^1/Z_2$ is discussed. The Standard Model (SM) fermions are introduced on one of the boundaries and some massive bulk fields are also introduced so that they couple to the SM fermions through the mass terms on the boundary. Integrating out the bulk fields generates SM fermion masses with exponentially small bulk mass dependences. The SM fermion masses except for the top quark are shown to be reproduced by mild tuning of the bulk masses. The one-loop Higgs potential is calculated and it is shown that electroweak symmetry breaking occurs by introducing additional bulk fields. The Higgs boson mass is also computed.

The Higgs boson: A major discovery and a problem

2019 ◽  
pp. 195-208
Author(s):  
Jean Zinn-Justin
Keyword(s):  
Higgs Boson ◽  
Particle Physics ◽  
Gauge Theories ◽  
Higgs Mechanism ◽  
Higgs Model ◽  
Fermion Mass ◽  
Simplified Models ◽  
Mass Generation ◽  
Abelian Gauge ◽  
The Standard Model

Chapter 12 describes the main steps in the construction of the electroweak component of the Standard Model of particle physics. The classical Abelian Landau–Ginzburg–Higgs mechanism is recalled, first introduced in the macroscopic description of a superconductor in a magnetic field. It is based on a combination of spontaneous symmetry breaking and gauge invariance. It can be generalized to non–Abelian gauge theories, quantized and renormalized. The recent discovery of the predicted Higgs boson has been the last confirmation of the validity of the model. Some aspects of the Higgs model and its renormalization group (RG) properties are illustrated by simplified models, a self–interacting Higgs model with the triviality issue, and the Gross–Neveu–Yukawa model with discrete chiral symmetry, which illustrates spontaneous fermion mass generation and possible RG flows.

scholarly journals SCALE OF MASS GENERATION FOR MAJORANA NEUTRINOS

2005 ◽  
Vol 20 (14) ◽  
pp. 3082-3088
Author(s):  
HONG-JIAN HE ◽  
DUANE A. DICUS
Keyword(s):  
Narrow Range ◽  
High Energy ◽  
Electroweak Symmetry Breaking ◽  
Fermion Mass ◽  
Electroweak Symmetry ◽  
Final State ◽  
Mass Generation ◽  
Upper Limit ◽  
Fermion Masses ◽  
Majorana Neutrinos

Scales of mass generation for Majorana neutrinos (as well as quarks and leptons) can be probed from high energy 2 → n inelastic scattering involving a multiple longitudinal gauge boson final state. We demonstrate that the unitarity of 2 → n scattering puts the strongest new upper limit on the scale of fermion mass generation, independent of the electroweak symmetry breaking scale [Formula: see text]. Strikingly, for Majorana neutrinos (quarks and leptons), we find that the strongest 2 → n limits fall in a narrow range, 136 - 170 TeV (3 - 107 TeV ) with n = 20 - 24 (n = 2 - 12), depending on the observed fermion masses. Physical implications are discussed.

Links between flavor and electroweak symmetry breaking

2014 ◽  
Vol 29 (21) ◽  
pp. 1444007
Author(s):  
George Wei-Shu Hou
Keyword(s):  
Symmetry Breaking ◽  
Scale Invariance ◽  
Vector Boson ◽  
New Physics ◽  
Electroweak Symmetry Breaking ◽  
Fermion Mass ◽  
Electroweak Symmetry ◽  
Mass Generation ◽  
Gap Equation ◽  
The Standard Model

Fermion mass generation in the standard model was invented by Weinberg, while it is an old notion that strong Yukawa coupling could be the agent of electroweak symmetry breaking. Observation of the 126 GeV boson has crashed the prospects for such a heavy chiral quark doublet Q. However, the dilaton possibility can only be ruled out by confirming vector boson fusion with Run 2 data at the LHC, which starts only in 2015. We recast the [Formula: see text] condensation scenario as Fermi–Yang model v2.0. A Gap Equation has been constructed, with numerical solution demonstrating dynamical mQ generation; scale invariance of this equation may be consistent with a dilaton. Other consequences to be checked are [Formula: see text] "annihilation stars," and enhanced Bd →μ+μ-, KL →π0νν, and possibly sin ϕs. If verified in Nature, the Agent of BEH mechanism would differ from current perception, the 126 GeV boson would be the first New Physics at the LHC, and we would have enough CP violation for baryogenesis.

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