scholarly journals Natural axion model from flavour

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Salvador Centelles Chuliá ◽  
Christian Döring ◽  
Werner Rodejohann ◽  
Ulises J. Saldaña-Salazar
Keyword(s):  
Particle Physics ◽  
Higgs Doublet ◽  
Fermion Mass ◽  
Simple Extension ◽  
Dark Matter Candidate ◽  
Type I ◽  
Mass Hierarchy ◽  
Standard Type ◽  
Yukawa Couplings ◽  
Fermion Masses

Abstract We explore a common symmetrical origin for two long standing problems in particle physics: the strong CP and the fermion mass hierarchy problems. The Peccei-Quinn mechanism solves the former one with an anomalous global U(1)PQ symmetry. Here we investigate how this U(1)PQ could at the same time explain the fermion mass hierarchy. We work in the context of a four-Higgs-doublet model which explains all quark and charged fermion masses with natural, i.e. order 1, Yukawa couplings. Moreover, the axion of the model constitutes a viable dark matter candidate and neutrino masses are incorporated via the standard type-I seesaw mechanism. A simple extension of the model allows for Dirac neutrinos.

scholarly journals Fermion mass hierarchy and g − 2 anomalies in an extended 3HDM Model

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
A. E. Cárcamo Hernández ◽  
Sergey Kovalenko ◽  
M. Maniatis ◽  
Ivan Schmidt
Keyword(s):  
Magnetic Moments ◽  
Higgs Doublet ◽  
Tree Level ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Strange Quarks ◽  
Lepton Flavor ◽  
Fermion Masses ◽  
Dark Matter Relic Density ◽  
The Masses

Abstract We propose an extension of the three-Higgs-doublet model (3HDM), where the Standard Model (SM) particle content is enlarged by the inclusion of two inert SU2L scalar doublets, three inert and two active electrically neutral gauge singlet scalars, charged vector like fermions and Majorana neutrinos. These additional particles are introduced to generate the SM fermion mass hierarchy from a sequential loop suppression mechanism. In our model the top and exotic fermion masses appear at tree level, whereas the remaining fermions get their masses radiatively. Specifically, bottom, charm, tau and muon masses appear at 1-loop; the masses for the light up, down and strange quarks as well as for the electron at 2-loop and masses for the light active neutrinos at 3-loop. Our model successfully accounts for SM fermion masses and mixings and accommodates the observed Dark Matter relic density, the electron and muon anomalous magnetic moments, as well the constraints arising from charged Lepton Flavor Violating (LFV) processes. The proposed model predicts charged LFV decays within the reach of forthcoming experiments.

scholarly journals Relaxing cosmological neutrino mass bounds with unstable neutrinos

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Miguel Escudero ◽  
Jacobo Lopez-Pavon ◽  
Nuria Rius ◽  
Stefan Sandner
Keyword(s):  
Neutrino Mass ◽  
Particle Physics ◽  
Goldstone Boson ◽  
Mass Scale ◽  
Simple Extension ◽  
Type I ◽  
Mass Generation ◽  
Age Of The Universe ◽  
Neutrino Mass Models ◽  
The Right

Abstract At present, cosmological observations set the most stringent bound on the neutrino mass scale. Within the standard cosmological model (ΛCDM), the Planck collaboration reports ∑mv< 0.12 eV at 95 % CL. This bound, taken at face value, excludes many neutrino mass models. However, unstable neutrinos, with lifetimes shorter than the age of the universe τν ≲ tU, represent a particle physics avenue to relax this constraint. Motivated by this fact, we present a taxonomy of neutrino decay modes, categorizing them in terms of particle content and final decay products. Taking into account the relevant phenomenological bounds, our analysis shows that 2-body decaying neutrinos into BSM particles are a promising option to relax cosmological neutrino mass bounds. We then build a simple extension of the type I seesaw scenario by adding one sterile state ν4 and a Goldstone boson ϕ, in which νi→ ν4ϕ decays can loosen the neutrino mass bounds up to ∑mv ∼ 1 eV, without spoiling the light neutrino mass generation mechanism. Remarkably, this is possible for a large range of the right-handed neutrino masses, from the electroweak up to the GUT scale. We successfully implement this idea in the context of minimal neutrino mass models based on a U(1)μ−τ flavor symmetry, which are otherwise in tension with the current bound on ∑mv.

scholarly journals Fermion mass hierarchies from supersymmetric gauged flavour symmetry in 5D

2021 ◽  
Vol 10 (6) ◽  
Author(s):  
Ketan Patel
Keyword(s):  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Fermion Mass ◽  
Order Unity ◽  
Anomaly Cancellation ◽  
Fundamental Parameters ◽  
Yukawa Couplings ◽  
Fifth Dimension ◽  
Fermion Masses ◽  
The Masses

A mechanism to generate realistic fermion mass hierarchies based on supersymmetric gauged U(1)_FU(1)F symmetry in flat five-dimensional (5D) spacetime is proposed. The fifth dimension is compactified on S^1/Z_2S1/Z2 orbifold. The standard model fermions charged under the extra abelian symmetry along with their superpartners live in the 5D bulk. Bulk masses of fermions are generated by the vacuum expectation value of N=2N=2 superpartner of U(1)_FU(1)F gauge field, and they are proportional to U(1)_FU(1)F charges of respective fermions. This decides localization of fermions in the extra dimension, which in turn gives rise to exponentially suppressed Yukawa couplings in the effective 4D theory. Anomaly cancellation puts stringent constraints on the allowed U(1)_FU(1)F charges which leads to correlations between the masses of quarks and leptons. We perform an extensive numerical scan and obtain several solutions for anomaly-free U(1)_FU(1)F, which describe the observed pattern of fermion masses and mixing with all the fundamental parameters of order unity. It is found that the possible existence of SM singlet neutrinos substantially improves the spectrum of solutions by offering more freedom in choosing U(1)_FU(1)F charges. The model predicts Z^\primeZ′ boson mediating flavour violating interactions in both the quark and lepton sectors with the couplings which can be explicitly determined from the Yukawa couplings.

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 A road towards a beyond the Standard Model model

2022 ◽  
Vol 258 ◽  
pp. 06003
Author(s):  
Giancarlo Rossi
Keyword(s):  
Standard Model ◽  
Chiral Symmetry ◽  
Top Quark ◽  
Gauge Coupling ◽  
Spontaneous Breaking ◽  
Strong Interactions ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Strongly Interacting ◽  
Fermion Masses

In this talk we describe examples of renormalizable strongly interacting field theories where chiral symmetry, broken at the UV cutoff by the presence of some irrelevant d > 4 operators in the fundamental Lagrangian, is recovered at low energy owing to the tuning of certain Lagrangian parameters. The interference of UV effects with IR features coming from the spontaneous breaking of the recovered chiral symmetry yields non perturbatively generated elementary fermion masses parametrically expressed by formulae of the kind mq ~ Cq(α)ΛRGI with α the gauge coupling constant and ΛRGI the RGI scale of the theory. Upon introducing EW interactions, this mechanism can be extended to give mass to EW bosons and leptons and can thus be used as an alternative to the Higgs scenario. In order to give the top quark and the weak gauge bosons a mass of the phenomenologically correct order of magnitude, the model must necessarily include (yet unobserved) super-strongly interacting massive fermions endowed, besides ordinary Standard Model interactions, with super-strong interactions with a RGI scale, ΛT ΛQCD in the few TeV range. Though limited in its scope (here we ignore hypercharge and leptons and discuss only the case of one family neglecting weak isospin splitting), the model opens the way to a solution of the naturalness problem and an understanding of the fermion mass hierarchy.

scholarly journals Improving fermion mass hierarchy in grand gauge–Higgs unification with localized gauge kinetic terms

2020 ◽  
Vol 80 (10) ◽  
Author(s):  
Nobuhito Maru ◽  
Yoshiki Yatagai
Keyword(s):  
Higgs Boson ◽  
Top Quark ◽  
Gauge Coupling ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Boson Mass ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Higgs Boson Mass ◽  
Fermion Masses

AbstractGrand gauge–Higgs unification of five dimensional SU(6) gauge theory on an orbifold $$S^1/Z_2$$ S 1 / Z 2 with localized gauge kinetic terms is discussed. The Standard model (SM) fermions on one of the boundaries and some massive bulk fermions coupling to the SM fermions on the boundary are introduced, so that they respect an SU(5) symmetry structure. The SM fermion masses including top quark are reproduced by mild tuning the bulk masses and parameters of the localized gauge kinetic terms. Gauge coupling universality is not guaranteed by the presence of the localized gauge kinetic terms and it severely constrains the Higgs vacuum expectation value. Higgs potential analysis shows that the electroweak symmetry breaking occurs by introducing additional bulk fermions in simplified representations. The localized gauge kinetic terms enhance the magnitude of the compactification scale, which helps Higgs boson mass large. Indeed the observed Higgs boson mass 125 GeV is obtained.

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.

scholarly journals Constraints on coloured scalars from global fits

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Otto Eberhardt ◽  
Víctor Miralles ◽  
Antonio Pich
Keyword(s):  
Top Quark ◽  
Scalar Potential ◽  
Higgs Doublet ◽  
Model Parameters ◽  
Simple Extension ◽  
Minimal Flavour Violation ◽  
Yukawa Couplings ◽  
Flavour Violation ◽  
The One ◽  
Potential Parameters

Abstract We consider a simple extension of the electroweak theory, incorporating one SU(2)L doublet of colour-octet scalars with Yukawa couplings satisfying the principle of minimal flavour violation. Using the HEPfit package, we perform a global fit to the available data, including all relevant theoretical constraints, and extract the current bounds on the model parameters. Coloured scalars with masses below 1.05 TeV are already excluded, provided they are not fermiophobic. The mass splittings among the different (charged and CP-even and CP-odd neutral) scalars are restricted to be smaller than 20 GeV. Moreover, for scalar masses smaller than 1.5 TeV, the Yukawa coupling of the coloured scalar multiplet to the top quark cannot exceed the one of the SM Higgs doublet by more than 80%. These conclusions are quite generic and apply in more general frameworks (without fine tunings). The theoretical requirements of perturbative unitarity and vacuum stability enforce relevant constraints on the quartic scalar potential parameters that are not yet experimentally tested.

scholarly journals Controlled fermion mixing and FCNCs in a ∆(27) 3+1 Higgs Doublet Model

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
A. E. Cárcamo Hernández ◽  
Ivo de Medeiros Varzielas ◽  
M. L. López-Ibáñez ◽  
Aurora Melis
Keyword(s):  
Neutrino Mass ◽  
Mass Parameter ◽  
Discrete Symmetry ◽  
Higgs Doublet ◽  
Spontaneous Breaking ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Neutrino Mass Hierarchy ◽  
Family Symmetry ◽  
Doublet Model

Abstract We propose a 3+1 Higgs Doublet Model based on the ∆(27) family symmetry supplemented by several auxiliary cyclic symmetries leading to viable Yukawa textures for the Standard Model fermions, consistent with the observed pattern of fermion masses and mixings. The charged fermion mass hierarchy and the quark mixing pattern is generated by the spontaneous breaking of the discrete symmetries due to flavons that act as Froggatt-Nielsen fields. The tiny neutrino masses arise from a radiative seesaw mechanism at one loop level, thanks to a preserved $$ {Z}_2^{(1)} $$ Z 2 1 discrete symmetry, which also leads to stable scalar and fermionic dark matter candidates. The leptonic sector features the predictive cobimaximal mixing pattern, consistent with the experimental data from neutrino oscillations. For the scenario of normal neutrino mass hierarchy, the model predicts an effective Majorana neutrino mass parameter in the range 3 meV ≲ mββ ≲ 18 meV, which is within the declared range of sensitivity of modern experiments. The model predicts Flavour Changing Neutral Currents which constrain the model, for instance, μ→e nuclear conversion processes and Kaon mixing are found to be within the reach of the forthcoming experiments.

scholarly journals Flavoured warped axion

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Quentin Bonnefoy ◽  
Peter Cox ◽  
Emilian Dudas ◽  
Tony Gherghetta ◽  
Minh D. Nguyen
Keyword(s):  
Scalar Field ◽  
Standard Model ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Complex Scalar ◽  
Fermion Masses ◽  
Complex Scalar Field ◽  
Hierarchy Problems

Abstract We consider a 5D extension of the DFSZ axion model that addresses both the axion quality and fermion mass hierarchy problems, and predicts flavour-dependent, off-diagonal axion-fermion couplings. The axion is part of a 5D complex scalar field charged under a U(1)PQ symmetry that is spontaneously broken in the bulk, and is insensitive to explicit PQ breaking on the UV boundary. Bulk Standard Model fermions interact with two Higgs doublets that can be localized on the UV boundary or propagate in the bulk to explain the fermion masses and mixings. When the Higgs doublets are localized on the UV boundary, they induce flavour diagonal couplings between the fermions and the axion. However, when the Higgs doublets propagate in the bulk, the overlap of the axion and fermion profiles generates flavour off-diagonal couplings. The effective scale of these off-diagonal couplings in both the quark and lepton sectors can be as small as 1011 GeV, and therefore will be probed in future precision flavour experiments.

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