scholarly journals A bottom-up approach to fermion mass hierarchy: a case with vector-like fermions

2020 ◽  
Vol 2020 (4) ◽  
Author(s):  
Yoshiharu Kawamura
Keyword(s):  
Standard Model ◽  
Yukawa Coupling ◽  
High Energy ◽  
Fine Tuning ◽  
Fermion Mass ◽  
Extended Model ◽  
Mass Hierarchy ◽  
Bottom Up ◽  
Existence Proofs ◽  
The Standard Model

Abstract We propose a bottom-up approach in which a structure of high-energy physics is explored by accumulating existence proofs and/or no-go theorems in the standard model or its extension. As an illustration, we study fermion mass hierarchies based on an extension of the standard model with vector-like fermions. It is shown that the magnitude of elements of Yukawa coupling matrices can become $O(1)$ and a Yukawa coupling unification can be realized in a theory beyond the extended model, if vector-like fermions mix with three families. In this case, small Yukawa couplings in the standard model can be highly sensitive to a small variation of matrix elements, and it seems that the mass hierarchy occurs as a result of fine tuning.

scholarly journals THE DUALIZED STANDARD MODEL AND ITS APPLICATIONS — AN INTERIM REPORT

1999 ◽  
Vol 14 (14) ◽  
pp. 2173-2203 ◽  
Author(s):  
HONG-MO CHAN ◽  
SHEUNG TSUN TSOU
Keyword(s):  
Standard Model ◽  
High Energy ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Matrix Elements ◽  
Ckm Matrix ◽  
High Energy Cosmic Rays ◽  
Perturbative Method ◽  
Ckm Matrix Elements ◽  
Physical Consequences

Based on a non-Abelian generalization of electric–magnetic duality, the Dualized Standard Model (DSM) suggests a natural explanation for exactly three generations of fermions as the "dual colour" [Formula: see text] symmetry broken in a particular manner. The resulting scheme then offers on the one hand a fermion mass hierarchy and a perturbative method for calculating the mass and mixing parameters of the Standard Model fermions, and on the other hand testable predictions for new phenomena ranging from rare meson decays to ultra-high energy cosmic rays. Calculations to one-loop order gives, at the cost of adjusting only three real parameters, values for the following quantities all (except one) in very good agreement with experiment: the quark CKM matrix elements ‖Vrs‖, the lepton CKM matrix elements ‖Urs‖, and the second generation masses mc, ms, mμ. This means, in particular, that it gives near maximal mixing Uμ3 between νμ and ντ as observed by SuperKamiokande, Kamiokande and Soudan, while keeping small the corresponding quark angles Vcb, Vts. In addition, the scheme gives (i) rough order-of-magnitude estimates for the masses of the lowest generation, (ii) predictions for low energy FCNC effects such as KL→ eμ, and (iii) a possible explanation for the long-standing puzzle of air showers beyond the GZK cut-off. All these together, however, still represent but a portion of the possible physical consequences derivable from the DSM scheme, the majority of which are yet to be explored.

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 Naturalness and Emergence

The Monist ◽  
2019 ◽  
Vol 102 (4) ◽  
pp. 499-524
Author(s):  
David Wallace
Keyword(s):  
Standard Model ◽  
High Energy Physics ◽  
High Energy ◽  
Fine Tuning ◽  
Entire Structure ◽  
The Standard Model ◽  
Intertheoretic Reduction ◽  
Energy Physics

Abstract I develop an account of naturalness (that is, approximately: lack of extreme fine-tuning) in physics which demonstrates that naturalness assumptions are not restricted to narrow cases in high-energy physics but are a ubiquitous part of how interlevel relations are derived in physics. After exploring how and to what extent we might justify such assumptions on methodological grounds or through appeal to speculative future physics, I consider the apparent failure of naturalness in cosmology and in the Standard Model. I argue that any such naturalness failure threatens to undermine the entire structure of our understanding of intertheoretic reduction, and so risks a much larger crisis in physics than is sometimes suggested; I briefly review some currently-popular strategies that might avoid that crisis.

scholarly journals Chasing after flavor symmetries of quarks from the bottom up

2019 ◽  
Vol 2019 (7) ◽  
Author(s):  
Yoshiharu Kawamura
Keyword(s):  
Standard Model ◽  
Yukawa Coupling ◽  
Beyond The Standard Model ◽  
Symmetric Part ◽  
Coupling Matrix ◽  
Bottom Up ◽  
Special Position ◽  
Flavor Symmetries ◽  
The Standard Model ◽  
Rank One

AbstractWe explore a flavor structure of quarks in the standard model under the assumption that flavor symmetries exist in a theory beyond the standard model, and seek their properties, using a bottom-up approach. We reacknowledge that a flavor-symmetric part of the Yukawa coupling matrix can be realized by a rank-one matrix, and a democratic-type matrix occupies a special position, based on Dirac’s naturalness.

scholarly journals Yukawa coupling unification in an SO(10) model consistent with Fermilab (g − 2)μ result

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Amin Aboubrahim ◽  
Pran Nath ◽  
Raza M. Syed
Keyword(s):  
Neural Network ◽  
Standard Model ◽  
Parameter Space ◽  
Yukawa Coupling ◽  
High Energy ◽  
Recent Analysis ◽  
Third Generation ◽  
High Luminosity ◽  
The Third ◽  
The Standard Model

Abstract We investigate the Yukawa coupling unification for the third generation in a class of SO(10) unified models which are consistent with the 4.2 σ deviation from the standard model of the muon g − 2 seen by the Fermilab experiment E989. A recent analysis in supergravity grand unified models shows that such an effect can arise from supersymmetric loops correction. Using a neural network, we further analyze regions of the parameter space where Yukawa coupling unification consistent with the Fermilab result can appear. In the analysis we take into account the contributions to Yukawas from the cubic and the quartic interactions. We test the model at the high luminosity and high energy LHC and estimate the integrated luminosities needed to discover sparticles predicted by the model.

scholarly journals On a mechanism realizing quark mass hierarchy

2020 ◽  
Vol 35 (33) ◽  
pp. 2050274
Author(s):  
Yoshiharu Kawamura
Keyword(s):  
Standard Model ◽  
Quark Mass ◽  
Fine Tuning ◽  
Mass Hierarchy ◽  
The Standard Model

We reconsider a generation of up-type quark mass hierarchy in the standard model and clarify how a mechanism works to realize the hierarchy without severe fine tuning.

scholarly journals A unified Yukawa interaction for the Standard Model of quarks and leptons

2021 ◽  
Vol 36 (27) ◽  
pp. 2150196
Author(s):  
Ying Zhang
Keyword(s):  
Standard Model ◽  
Mass Matrix ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Yukawa Interaction ◽  
Flavor Structure ◽  
Fermion Masses ◽  
The Standard Model ◽  
Matrix Formula

To address fermion mass hierarchy and flavor mixings in the quark and lepton sectors, a minimal flavor structure without any redundant parameters beyond phenomenological observables is proposed via decomposition of the Standard Model Yukawa mass matrix into a bi-unitary form. After reviewing the roles and parameterization of the factorized matrix [Formula: see text] and [Formula: see text] in fermion masses and mixings, we generalize the mechanism to up- and down-type fermions to unify them into a universal quark/lepton Yukawa interaction. In the same way, a unified form of the description of the quark and lepton Yukawa interactions is also proposed, which shows a similar picture as the unification of gauge interactions.

scholarly journals A first test of the framed standard model against experiment

2015 ◽  
Vol 30 (11) ◽  
pp. 1550051 ◽  
Author(s):  
José Bordes ◽  
Hong-Mo Chan ◽  
Sheung Tsun Tsou
Keyword(s):  
Standard Model ◽  
Mass Matrix ◽  
Internal Symmetry ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Order Unity ◽  
Changing Scale ◽  
The Standard Model ◽  
Symmetry Space ◽  
Fermion Mass Matrix

The framed standard model (FSM) is obtained from the standard model by incorporating, as field variables, the frame vectors (vielbeins) in internal symmetry space. It gives the standard Higgs boson and 3 generations of quarks and leptons as immediate consequences. It gives moreover a fermion mass matrix of the form: m = mTαα†, where α is a vector in generation space independent of the fermion species and rotating with changing scale, which has already been shown to lead, generically, to up–down mixing, neutrino oscillations and mass hierarchy. In this paper, pushing the FSM further, one first derives to 1-loop order the RGE for the rotation of α, and then applies it to fit mass and mixing data as a first test of the model. With 7 real adjustable parameters, 18 measured quantities are fitted, most (12) to within experimental error or to better than 0.5 percent, and the rest (6) not far off. (A summary of this fit can be found in Table 2 of this paper.) Two notable features, both generic to FSM, not just specific to the fit, are: (i) that a theta-angle of order unity in the instanton term in QCD would translate via rotation into a Kobayashi–Maskawa phase in the CKM matrix of about the observed magnitude (J ~ 10-5), (ii) that it would come out correctly that mu < md, despite the fact that mt ≫ mb, mc ≫ ms. Of the 18 quantities fitted, 12 are deemed independent in the usual formulation of the standard model. In fact, the fit gives a total of 17 independent parameters of the standard model, but 5 of these have not been measured by experiment.

scholarly journals Planck Neutrinos as Ultra High Energy Cosmic Rays

2020 ◽  
Vol 29 (1) ◽  
pp. 40-46
Author(s):  
Dmitri L. Khokhlov
Keyword(s):  
Black Holes ◽  
Cosmic Rays ◽  
Standard Model ◽  
Active Galactic Nuclei ◽  
Planck Scale ◽  
Galactic Nuclei ◽  
High Energy ◽  
Ultra High Energy ◽  
High Energy Cosmic Rays ◽  
The Standard Model

AbstractThe studied conjecture is that ultra high energy cosmic rays (UHECRs) are hypothetical Planck neutrinos arising in the decay of the protons falling onto the gravastar. The proton is assumed to decay at the Planck scale into positron and four Planck neutrinos. The supermassive black holes inside active galactic nuclei, while interpreted as gravastars, are considered as UHECR sources. The scattering of the Planck neutrinos by the proton at the Planck scale is considered. The Planck neutrinos contribution to the CR events may explain the CR spectrum from 5 × 1018 eV to 1020 eV. The muon number in the Planck neutrinos-initiated shower is estimated to be larger by a factor of 3/2 in comparison with the standard model that is consistent with the observational data.

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