Study of the Relation Between Charged Yukawa Coupling Constants Under the Leptonic Specific Two Higgs Doublet Model

We consider self-gravitating Skyrmions in the presence of Dirac fermions, that carry spin and isospin. By varying the gravitational and the Yukawa coupling constants, we investigate the spectral flow of the fermion eigenvalue associated with a zero mode in the absence of gravity. We demonstrate that the backreaction of the fermion can strongly influence the Skyrmion-fermion configurations. In particular, the energy conditions may be violated, and regular anti-gravitating asymptotically flat solutions with negative ADM mass may emerge.

In the context of the two Higgs doublet model type III with flavor-changing neutral currents at the tree level, I obtain non-universality relationships of charged Higgs boson Yukawa coupling constants by calculating the widths of the pure leptonic decays of the tau lepton τ→eν¯eντ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au \\rightarrow e \\bar{\ u }_e \ u _\ au$$\\end{document} and τ→μν¯μντ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au \\rightarrow \\mu \\bar{\ u }_\\mu \ u _\ au$$\\end{document}. To this end, I first calculate these total widths by including the effects of the exchanges of the Higgs boson H-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H^-$$\\end{document} and the gauge boson W-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$W^-$$\\end{document}, with the purpose to obtain the flavor-violating contribution ΔlH-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta _l^{H^-}$$\\end{document} and then to calculate the fraction ΔμH-/ΔeH-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta _\\mu ^{H^-}/\\Delta _e^{H^-}$$\\end{document}. By writing this fraction in terms of the experimental and electroweak standard model branching ratios of these decays and assuming that flavors of neutrino and antineutrino in the final state are defined but unknown, I obtain fractions of charged Higgs boson Yukawa coupling constants that differ from one. These fractions establish non-universality relationships associated with the scalar interaction in contrast to the universality relationships associated with the electroweak interaction.

We propose a grand unified theory (GUT) pseudo-Nambu-Goldstone boson (pNGB) dark matter (DM) model based on SU(7) gauge symmetry. In the GUT model, the Standard Model (SM) gauge symmetry GSM≔SU(3)C×SU(2)L×U(1)Y and the “dark” gauge symmetry SU(2)D are unified, where the SU(2)D symmetry plays an important role in the stability of DM. The unification of SM fermions and dark sector fermions is partially realized. The gauge symmetry SU(7) is spontaneously broken to SU(5)×SU(2)×U(1) gauge symmetry at the GUT scale by the nonvanishing vacuum expectation values of an SU(7) adjoint scalar field, where the SU(5) gauge symmetry is not usual SU(5) GUT gauge symmetry. The symmetry is further broken to GSM×SU(2)D at an intermediate scale. Furthermore, the SU(2)D symmetry is broken by the SU(2)D doublet and triplet scalar fields at the TeV scale. In the pNGB DM model based on GSM×SU(2)D, the residual global U(1)V dark custodial symmetry guarantees DM stability. On the other hand, in the SU(7) pNGB DM model, this global symmetry is explicitly broken by the Yukawa interaction and the effective Majorana mass terms. In the scalar sector, the cubic coupling constants of the SU(2)D doublet and triplet scalar fields are the order parameters of the U(1)V symmetry breaking. To maintain U(1)V symmetry and thus the DM stability, we need to tune Yukawa coupling constants and cubic scalar couplings at high accuracy. We find that the allowed DM mass region is quite restricted as the gauge coupling constant of SU(2)D is determined by the condition of the gauge coupling unification. To satisfy gauge coupling unification and the current experimental constraint on proton lifetime, we find that three generations of SU(3)C adjoint fermions and another three generations of SU(2)L adjoint fermions with the intermediate mass scale are required. We also find that there is no other solution to satisfy simultaneously the gauge coupling unification and the proton decay constraint if one assumes the other symmetry breaking schemes. Published by the American Physical Society 2024

The scattering of massless fermions on a one-dimensional Q-ball is studied both analytically and numerically in the background field approximation. The wave functions of the fermionic scattering states are found in analytical form. General expressions are derived for the transmission and reflection coefficients and the corresponding S-matrix elements. General formulae describing the evaporation of the Noether charge of the one-dimensional Q-ball are given. A numerical study of the transmission and reflection coefficients along with the corresponding S-matrix elements is performed for a range of values of the model parameters. A study of the dependence of the evaporation rate of the Q-ball on the Yukawa coupling constant is carried out for several values of the Noether charge.

Measuring the fermion Yukawa coupling constants is important for understanding the origin of the fermion masses and their relationship with spontaneously electroweak symmetry breaking. In contrast, some new physics (NP) models change the Lorentz structure of the Yukawa interactions between standard model (SM) fermions and the SM-like Higgs boson, even in their decoupling limit. Thus, the precise measurement of the fermion Yukawa interactions is a powerful tool of NP searching in the decoupling limit. In this work, we show the possibility of investigating the Lorentz structure of the bottom-quark Yukawa interaction with the 125 GeV SM-like Higgs boson for future colliders.

We consider the Standard Model with three right-handed neutrinos to generate tiny neutrino masses by the seesaw mechanism. Especially, we investigate the case when one right-handed neutrino has the suppressed Yukawa coupling constants. Such a particle has a long lifetime and can produce an additional entropy by the decay. It is then discussed the impact of the entropy production on the gravitational wave background originated in the primordial inflation. We show that the mass and the coupling constants of the long-lived right-handed neutrino can be probed by the distortion of the gravitational wave spectrum, leading to the information of the mass of the lightest active neutrino.

Three repetitive chiral fields of quarks and leptons are bundled to form clusters, called chiral-triplets, in the electroweak symmetric regime. Postulating that each chiral-triplets possesses its own Clifford-Dirac algebra with the common Lorentz subalgebra and that the gauge fields and the Higgs field interact with the chiral-triplets, we renovate the Standard Model of elementary particles so that the uncertainties persisted in the Yukawa interactions are reduced. The vertex of the interaction between the Higgs field and the chiral-triplets includes pairs of unipotent matrices and four parameters generating the nine Yukawa coupling constants in the Standard Model. The small masses of light active neutrinos arise from the seesaw mechanism induced from the Majorana mass of the right-handed neutrinos. The Higgs mechanism leads to the Dirac mass matrices which can describe all data of the mass spectra and the flavor mixing matrices in the quark and lepton sectors to high precision.

We consider a model with three right-handed neutrinos in which Yukawa coupling constants and Majorana masses are obtained by requiring the modular A4 symmetry. It has been shown that the model can explain mass hierarchies and mixing patterns of charged leptons and neutrinos with the seesaw mechanism. In this article we investigate the leptogenesis by decays of right-handed neutrinos in this model. It is shown that masses of right-handed neutrinos are about 1013 GeV in order to account for the observed baryon asymmetry of the universe. Furthermore, the positive sign of the baryon asymmetry is obtained only for the limited ranges of mixing angles and CP violation phases of active neutrinos, which can be tested by future neutrino experiments.

A novel model of charged leptons is presented, which contains two basics hypotheses. The first hypothesis is that the Yukawa coupling between Higgs field and charged leptons is the weak interaction, the Higgs field is a scalar intermediate boson which changes the chirality of charged leptons in the weak interaction. The other hypothesis is that the flavor eigenstates of charged leptons are the superposition states of left-handed and right-handed elementary Weyl spinors before the electroweak symmetry breaking. According to this model, the Yukawa coupling constants between Higgs field and three generations of charged leptons are considered to be a universal constant, and the difference of the masses of different charged leptons is due to the different left-right mixing angles of their flavor eigenstates.

We investigate the Higgs-Yukawa system with Majorana masses of a fermion within asymptotically safe quantum gravity. Using the functional renormalization group method we derive the beta functions of the Majorana masses and the Yukawa coupling constant and discuss the possibility of a non-trivial fixed point for the Yukawa coupling constant. In the gravitational sector we take into account higher derivative terms such as R2 and RμνRμν in addition to the Einstein-Hilbert term for our truncation. For a certain value of the gravitational coupling constants and the Majorana masses, the Yukawa coupling constant has a non-trivial fixed point value and becomes an irrelevant parameter being thus a prediction of the theory. We also discuss consequences due to the Majorana mass terms to the running of the quartic coupling constant in the scalar sector.

We revisited the scenario of electroweak baryogenesis in the presence of large Yukawa couplings, in which it was found previously that a strongly first order electroweak phase transition can occur with the Higgs mass at its observed value of 125 GeV. Given the sensitivity of the running of the Higgs quartic coupling on the Yukawa coupling constants, we find that the addition of order one Yukawa couplings beyond the top quark drastically lowers the scale at which the Higgs potential becomes unstable. Specifically, even with only one additional order one Yukawa coupling, the scalar potential becomes unstable already at the TeV scale, assuming the Standard Model values for the Higgs sector parameters at the electroweak scale. Furthermore, by assuming the Standard Model values for the Higgs sector parameters at the TeV scale, the quartic coupling constant is driven to be larger than its Standard Model value at the electroweak scale. This in turn predicts a much lighter Higgs mass than the measured value of 125 GeV. In this scenario, the strength of the electroweak phase transition is also significantly weakened.

Thermal production of light Dirac right-handed sneutrino dark matter

The flavor problem, neutrino physics and the fermion mass hierarchy are\nimportant motivations to extend the Standard Model into the TeV scale. A new\nfamily non-universal extension is presented with three Higgs doublets, one\nHiggs singlet and one scalar dark matter candidate. Exotic fermions are\nincluded in order to cancel chiral anomalies and to allow family non-universal\n$\\mathrm{U(1)}_{X}$ charges. By implementing an additional $\\mathbb{Z}_{2}$\nsymmetry the Yukawa coupling terms are suited in such a way that the fermion\nmass hierarchy is obtained without fine-tuning. The neutrino sector include\nMajorana fermions to implement inverse see-saw mechanism. The effective mass\nmatrix for SM neutrinos is fitted to current neutrino oscillation data to check\nthe consistency of the model with experimental evidence, obtaining that the\nnormal-ordering scheme is preferred over the inverse ones and the values of the\nneutrino Yukawa coupling constants are shown. Finally, the $h\\rightarrow\n\\tau\\mu$ lepton-flavor-violation process is addressed with the rotation\nmatrices of the CP-even scalars, left- and right-handed charged leptons,\nyielding definite regions where the model is consistent with CMS reports of\n$\\mathrm{BR}(h\\rightarrow \\tau\\mu)$.\n Keywords: Flavor Problem, Neutrino Physics, Extended Scalar Sectors, Beyond\nStandard Model, Fermion masses, Inverse See-Saw Mechanism, LFV.\n

We study asymptotic safety of models of the higher derivative quantum gravity with and without matter. The beta functions are derived by utilizing the functional renormalization group, and non-trivial fixed points are found. It turns out that all couplings in gravity sector, namely the cosmological constant, the Newton constant, and the R2 and Rμν2 coupling constants, are relevant in case of higher derivative pure gravity. For the Higgs-Yukawa model non-minimal coupled with higher derivative gravity, we find a stable fixed point at which the scalar-quartic and the Yukawa coupling constants become relevant. The relevant Yukawa coupling is crucial to realize the finite value of the Yukawa coupling constants in the standard model.

We consider $b$-$\tau$ unification in supersymmetric $SU(5)$ grand unified theories (GUTs) with extra matters. The renormalization group runnings of $b$ and $\tau$ Yukawa coupling constants may be significantly affected by the existence of extra matters. If the extra matters interact with the standard model particles (and their superpartners) only through gauge interaction, the ratio of the $b$ to $\tau$ Yukawa coupling constants at the GUT scale becomes suppressed compared to the case without extra matters. This is mainly due to the change of the renormalization group running of the $SU(3)_C$ gauge coupling constant. If the extra matters have Yukawa couplings, on the contrary, the (effective) $b$ Yukawa coupling at the GUT scale can be enhanced due to the new Yukawa interaction. Such an effect may improve the $b$-$\tau$ unification in supersymmetric GUTs.

A two-dimensional model involving a fermion field and a self-interacting scalar field with Yukawa interaction is studied beyond the one-loop approximation. It is shown that, in this model, the chiral condensate vanishes at two values of the Yukawa coupling constant. In one case, the respective symmetry is restored, while, in the other case, it is not restored.

A two-loop induced radiative neutrino model is proposed as an extension of\nour previous work in which the first and second generation standard model\nfermion masses are generated at one-loop level in both quark and lepton\nsectors. Then we discuss current neutrino oscillation data, lepton flavor\nviolations, muon anomalous magnetic moment, and a bosonic dark matter\ncandidate, for both the normal and inverted neutrino mass hierarchy. Our\nnumerical analysis shows that less hierarchical Yukawa coupling constants can\nfit the experimental data with TeV scale dark matter.\n

We study the Yukawa unification, in particular, the unification of the Yukawa coupling constants of $b$ and $\tau$, in the framework of supersymmetric (SUSY) model. We concentrate on the model in which the SUSY breaking scalar masses are of the order of the gravitino mass while the gaugino masses originate from the effect of anomaly mediation and hence are one-loop suppressed relative to the gravitino mass. We perform an accurate calculation of the Yukawa coupling constants of $b$ and $\tau$ at the grand unified theory (GUT) scale, including relevant renormalization group effects and threshold corrections. In particular, we study the renormalization group effects, taking into account the mass splittings among sfermions, gauginos, and the standard model particles. We found that the Yukawa coupling constant of $b$ at the GUT scale is about $70\ \%$ of that of $\tau$ if there is no hierarchy between the sfermion masses and the gravitino mass. Our results suggest sizable threshold corrections to the Yukawa coupling constants at the GUT scale or significant suppressions of the sfermion masses relative to the gravitino mass.

We study the fixed-point structure of the Higgs–Yukawa model, with its scalar being non-minimally coupled to the asymptotically safe gravity, using the functional renormalization group. We have obtained the renormalization group equations for the cosmological and Newton constants, the scalar mass squared and quartic coupling constant, and the Yukawa and non-minimal coupling constants, taking into account all the scalar, fermion, and graviton loops. We find that switching on the fermionic quantum fluctuations makes the non-minimal coupling constant irrelevant around the Gaussian-matter fixed point with asymptotically safe gravity.