arXiv subjects

Masaki J. S. Yang

Publications and source records attributed to Masaki J. S. Yang.

48 records · Page 3Linked to original sources

arXiv2018

Flavor structure from flavored Higgs mixing

In this paper, we suggest a simple model which induces realistic flavor structure from mixing of flavored Higgs doublets. The idea is based on the decoupling limit. In a model with many Higgs doublets, the mass eigenstates of scalars are linear combinations of Higgs doublets. If the mass matrix of Higgs fields has only one massless mode, and if the linear combination has flavor dependence, the induced Yukawa coupling will have nontrivial flavor structure. We suggest a mass matrix of flavored Higgs fields in a $U(2)_{L} \times U(2)_{R}$ toy model. An advantage of this model is that all of the elements in Yukawa matrix can be determined from renormalizable Higgs potential.

hep-ph↗

arXiv2017

Flavor structure from misalignment of inner products in noncommutative geometry

In this letter, we consider an idea that induces flavor structure from inner products in noncommutative geometry. Assuming proper components of vectors $v_{(L,R) i}$ in enlarged representation space for fermions, we can induce the waterfall texture for Yukawa matrices retaining gauge interactions are universal. The hierarchy of the Yukawa interactions is a consequence of "misalignment" between the vectors $v_{Li}$ and $v_{Rj}$.

hep-ph↗

arXiv2017

Nontrivial Flavor Structure from Noncompact Lie Group in Noncommutative Geometry

In this paper, we propose a mechanism which induces nontrivial flavor structure from transformations of a noncompact Lie group SL(3,C) in noncommutative geometry. Matrices $L \in$ SL(3,C) are associated with accompanied by the preon fields as $a_{L,R} (x) \to L_{L,R} a_{L,R} (x)$. In order to retain the Hermiticity of the Lagrangian, we assume the same trick when $ψ^{\dagger} ψ$ is replaced by $\bar ψψ$ to construct a Lorentz invariant Lagrangian. As a result, the Dirac Lagrangian has both of flavor-universal gauge interactions and nontrivial Yukawa interactions. Removing the unphysical unitary transformations, Yukawa matrices found to be $Y_{ij} = L_{L}^{\dagger} k L_{R} \to Λ_{L}^{} U^{\dagger}_{L} k U_{R} Λ_{R}$. Here, $k$ is a coefficient, $U$ is 3 $\times$ 3 unitary matrix and $Λ$ is the eigenvalue matrix $Λ= {\rm diag}(λ_{1}, λ_{2}, λ_{3})$ with $λ_{1}λ_{2}λ_{3} = 1$. If $L_{L,R}$ are originated from a broken symmetry, the hierarchy and mixing of flavor can be interpreted as the "Lorentz boost" and the "rotation" in this space respectively.

hep-ph↗

arXiv2017

A possibility on prohibition of Higgs mass by the extended Lorentz transformation in noncommutative geometry

In this letter, we propose the extended Lorentz transformation in noncommutative geometry, as a possibility on prohibition of the Higgs mass. Since it is difficult to build the symmetry between the connections $A_μ$ and $H$, the transformation is defined for the differential two-forms. The parameter of the transformation $ω$ changes a two-form into other two-forms. Comparing the coefficients of the two-forms, the transformations are translated to those of the product fields $F_{μν}, D_μ H$ and $HH^{\dagger}$. It shows the invariance of the bosonic Lagrangian explicitly.

hep-ph↗

arXiv2017

Analysis of right-handed Majorana neutrino mass in an $SU(4) \times SU(2)_{L} \times SU(2)_{R}$ Pati--Salam model with democratic texture

In this paper, we attempt to build an unified model with democratic texture, that have some unification between $Y_ν$ and $Y_{u}$. Since the $S_{3L} \times S_{3R}$ flavor symmetry is chiral, the unified gauge group is assumed to be Pati-Salam type $SU(4)_{c} \times SU(2)_{L} \times SU(2)_{R}$. The flavor symmetry breaking scheme is considered to be $S_{3L} \times S_{3R} \to S_{2L} \times S_{2R} \to 0$. In this picture, the four-zero texture is desirable for realistic mass and mixings. This texture is realized by a specific representation for the second breaking of the $S_{3L} \times S_{3R}$ flavor symmetry. Assuming only renormalizable Yukawa interactions, type-I seesaw mechanism, and neglecting $CP$ phases for simplicity, the right-handed neutrino mass matrix $M_{R}$ can be reconstructed from low energy input values. Numerical analysis shows that the texture of $M_{R}$ basically behaves like the "waterfall texture". Since $M_{R}$ tends to be the "cascade texture" in the democratic texture approach, a model with type-I seesaw and up-type Yukawa unification $Y_ν \simeq Y_{u}$ basically requires fine-tunings between parameters. Therefore, it seems to be more realistic to consider universal waterfall textures for both $Y_{f}$ and $M_{R}$, e.g., by the radiative mass generation or the Froggatt--Nielsen mechanism. Moreover, analysis of eigenvalues shows that the lightest mass eigenvalue $M_{R1}$ is too light to achieve successful thermal leptogenesis. Although the resonant leptogenesis might be possible, it also requires fine-tunings of parameters.

hep-ph↗

arXiv2016

Hierarchical majorana neutrinos from democratic mass matrices

In this paper, we obtain the light neutrino masses and mixings consistent with the experiments, in the democratic texture approach. The essential ansatz is that $ν_{Ri}$ are assumed to transform as "right-handed fields" $\bf 2_{R} + 1_{R}$ under the $S_{3L} \times S_{3R}$ symmetry. The symmetry breaking terms are assumed to be diagonal and hierarchical. This setup only allows the normal hierarchy of the neutrino mass, and excludes both of inverted hierarchical and degenerated neutrinos. Although the neutrino sector has nine free parameters, several predictions are obtained at the leading order. When we neglect the smallest parameters $ζ_ν$ and $ζ_{R}$, all components of the mixing matrix $U_{\rm PMNS}$ are expressed by the masses of light neutrinos and charged leptons. From the consistency between predicted and observed $U_{\rm PMNS}$, we obtain the lightest neutrino masses $m_{1}$ = (1.1 $\to$ 1.4) meV, and the effective mass for the double beta decay $\vev{m_{ee}} \simeq$ 4.5 meV.

hep-ph↗

arXiv2015

A symmetry breaking mechanism by parity assignment in the noncommutative Higgs model

We apply the orbifold grand unified theory (GUT) mechanism to the noncommutative Higgs model. An assignment of $Z_{2}$ parity to the "constituent fields" induces parity assignments of both the gauge and Higgs bosons, because these bosons are treated as some kind of composite field in this formalism. As a result, some of the gauge bosons and the colored triplet Higgs boson receive heavy mass comparable to the GUT scale, and the gauge symmetry is broken. No particles appear other than the SM ones in the massless states.

hep-ph↗

arXiv2015

Reconstruction of the standard model with classical conformal invariance in noncommutative geometry

In this paper, we derive the standard model with classical conformal invariance from the Yang--Mills--Higgs model in noncommutative geometry (NCG). In the ordinary context of the NCG, the {\it distance matrix} $M_{nm}$ which corresponds to the vacuum expectation value of Higgs fields is taken to be finite. However, since $M_{nm}$ is arbitrary in this formulation, we can take all $M_{nm}$ to be zero. In the original composite scheme, the Higgs field itself vanishes with the condition $M_{nm} = 0$. Then, we adopt the elemental scheme, in which the gauge and the Higgs bosons are regarded as elemental fields. By these assumptions, all scalars do not have vevs at tree level. The symmetry breaking mechanism will be implemented by the Coleman--Weinberg mechanism. As a result, we show a possibility to solve the hierarchy problem in the context of NCG. Unfortunately, the Coleman--Weinberg mechanism does not work in the SM Higgs sector, because the Coleman--Weinberg effective potential becomes unbounded from below for $m_{t} > m_{Z}$. However, viable models can be possible by proper extensions.

hep-ph↗

arXiv2015

Nilpotent Matrix Representation of Exterior Derivative Operator in Noncommutative Geometry

In this letter, we show a nilpotent matrix representation of the exterior derivative operator in noncommutative geometry (NCG), by translating the noncommutative relations of the algebraic formalization into the original one. As a result, we can construct the extended gauge theory without complicated algebraic rules nor excessively large differential algebra and non-monomorphic representation.

hep-th↗

arXiv2015

SU(5) orbifold GUT in noncommutative geometry

In this paper, we appliy the orbifold GUT mechanism to the SU(5) model in noncommutative geometry, including the fermonic sector. Imposing proper parity assignments for "constituent fields" of bosons and fermions, the couplings between fermions and the heavy bosons $X_μ, Y_μ$, and $ H^{c}$ are prohibited by the parity symmetry. As a result, the derived fermionic Lagrangian is just that of the standard model, and proton decay is forbidden at tree level. If quantum fluctuation respects the parity symmetry, the process will be naturally suppressed or even forbidden completely.

hep-ph↗

arXiv2012

QCD Corrections to Neutron Electric Dipole Moment from Dimension-six Four-Quark Operators

In this paper, the renormalization-group equations for the (flavor-conserving) CP-violating interaction are derived up to the dimension six, including all the four-quark operators, at one-loop level. We apply them to the models with the neutral scalar boson or the color-octet scalar boson which have CP-violating Yukawa interactions with quarks, and discuss the neutron electric dipole moment in these models.

hep-ph↗

arXiv2009

Upward muon signals at neutrino detectors as a probe of dark matter properties

We study upward muon flux at neutrino detectors such as Super-Kamiokande resulting from high-energy neutrinos produced by the dark matter annihilation/decay at the Galactic center. In particular, we distinguish showering and non-showering muons as their energy loss processes inside the detector, and show that this information is useful for discriminating dark matter models.

hep-ph↗