arXiv subjects

Yoshio Koide

Publications and source records attributed to Yoshio Koide.

At least 37 records · Page 2Linked to original sources

arXiv2015

Origin of Hierarchical Structures of Quark and Lepton Mass Matrices

It is shown that the so-called "Yukawaon" model can give a unified description of masses, mixing and $CP$ violation parameters of quarks and leptons without using any hierarchical (family number-dependent) parameters besides the charged lepton masses. Here, we have introduced a phase matrix $P={\rm daig}(e^{i ϕ_1}, e^{i ϕ_2}, e^{i ϕ_3})$ with the phase parameters $(ϕ_1, ϕ_2, ϕ_3)$ which are described in terms of family number-independent parameters, together with using only the charged lepton mass parameters as the family number-dependent parameters. In this paper, the $CP$ violating phase parameters $δ_{CP}^q$ and $δ_{CP}^\ell$ in the standard expression of $V_{CKM}$ and $U_{PMNS}$ are predicted as $δ_{CP}^q \simeq 72^\circ$ and $δ_{CP}^\ell \simeq -76^\circ$, respectively, i.e. $δ_{CP}^\ell \sim - δ_{CP}^q$.

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arXiv2014

Phenomenology of Harmless Family Gauge Bosons to $K^0$-$\bar{K}^0$ Mixing

When we try to consider family gauge bosons with a lower energy scale, a major obstacle is constraints from the observed $P^0$-$\bar{P}^0$ mixings ($P^0=K^0, D^0, B^0,B^0_s$). Against such a conventional view, we point out that, in a U(3) family gauge boson model, the bosons are harmless to any $P^0$-$\bar{P}^0$ mixings independently of explicit values of the family mixings, if masses $M_{ij}$ of the gauge bosons $A_i^{\ j}$ ($i,j$ are family indexes) satisfy a relation $2/M_{ij}^2=1/M_{ii}^2 +1/M_{jj}^2$. If such the case can be realized together with an inverted mass hierarchy $M_{33}^2 \ll M_{22}^2 \ll M_{11}^2$, we can consider family gauge bosons with a considerably lower scale, so that we can expect rich signs for family gauge bosons in a TeV scale.

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arXiv2014

Leptonic $CP$ violating Phase in the Yukawaon Model

In the so-called "Yukawaon" model, the (effective) Yukawa coupling constants $Y_f^{eff}$ are given by vacuum expectation values (VEVs) of scalars $Y_f$ (Yukawaons) with $3\times 3$ components. In this brief report, we change VEV forms $ $ in the previous paper into a unified form. Therefore, parameter fitting for quark and lepton masses and mixings is revised. Especially, we obtain predicted values of neutrino mixing $\sin^2 2θ_{13}$ and a leptonic $CP$ violating phase $δ_{CP}^\ell$ which are consistent with the observed curve in the $(\sin^2 2θ_{13}, δ_{CP}^\ell)$ reported by T2K group recently.

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arXiv2014

Spectroscopy of Family Gauge Bosons

Spectroscopy of family gauge bosons is investigated based on a U(3) family gauge boson model proposed by Sumino. In his model, the family gauge bosons are in mass eigenstates in a diagonal basis of the charged lepton mass matrix. Therefore, the family numbers are defined by $(e_1,e_2, e_3)=(e, μ, τ)$, while the assignment for quark sector are free. For possible family-number assignments $(q_1, q_2, q_3)$, under a constraint from $K^0$-$\bar{K}^0$ mixing, we investigate possibilities of new physics, e.g. production of the lightest family gauge boson at the LHC, $μ^- N \rightarrow e^- N$, rare $K$ and $B$ decays, and so on.

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arXiv2014

Universal Bilinear Form of Quark and Lepton Mass Matrices

In the so-called ``yukawaon" model, the (effective) Yukawa coupling constants $Y_f^{eff}$ are given by vacuum expectation values (VEVs) of scalars $Y_f$ (yukawaons) with $3\times 3$ components. In the present model, all of the VEV matrices $\langle Y_f \rangle$ are given by a bilinear form of VEVs of flavons $Φ_f$, $\langle Y_f \rangle_i^{\ j} = k_f \langle Φ_f\rangle_{ik} \langle \barΦ_f\rangle^{kj}$, where $Φ_f$ is assigned to ${\bf 6}$ of U(3) family symmetry. As input parameters with family-number dependent values, we use only charged lepton mass values. Under this formulation, we can give reasonable values of quark and lepton masses and their mixings. A $CP$ violating phase $δ_{CP}^\ell=26^\circ$ in the lepton sector is predicted. The effective Majorana neutrino mass is also predicted.

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arXiv2014

Effective Valence Quark Model and a Possible Dip in $d Br(B \to K \ell \bar{\ell})/dq^2$

In rare $B$ meson decays $B\rightarrow K \ell^+ \ell^-$, a possible contribution of $\ell^+\ell^-$ emission via photon from the "spectator" quark $q$ ($q=u,d$) in the $B$ meson $(q\bar{b})$ is investigated in addition to the conventional one $\bar{b} \rightarrow \bar{s} +γ\rightarrow \bar{s}+\ell^+ + \ell^-$. If such a contribution is sizable compared with the standard estimation of $B\rightarrow K \ell^+ \ell^-$, we will observe visible difference between $d Γ(B^0\rightarrow K^0 \ell^+ \ell^-)/d q^2$ and $d Γ(B^+\rightarrow K^+ \ell^+ \ell^-)/d q^2$ in $q^2$ dependence ($q^2 \equiv m_{\ell\ell}^2$). Besides, as a result of the interference between the conventional one and a new one, a dip appears in $d Γ(B\rightarrow K \ell^+ \ell^-)/d q^2$ at a small region of $q^2$. The interference effect in the $B^0$ decay will also be observed differently from that in the $B^+$ decay. The calculation is done based on a semi-classical approach, a valence quark model. In the present model, the photon emission from the spectator quark $q$, $d \rightarrow d+γ$ ($u \rightarrow u+γ$) is independent of the $b$-$s$ transition mechanism, and the characteristic results are due to a straightforward estimate of the quark propagator which cannot be incorporated into the factorization method. The model is not a valence quark "dominant" model, so that, for example, the valence quarks in the final state carry only $24\%$ of the energy-momentum of the kaon.

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arXiv2013

Yukawaon Model with Anomaly Free Set of Quarks and Leptons in a U(3) Family Symmetry

In the so-called "yukawaon" model, the (effective) Yukawa coupling constants $Y_f^{eff}$ are given by vacuum expectation values (VEVs) of scalars $Y_f$ (yukawaons) with $3\times 3$ components. So far, yukawaons $Y_f$ have been assigned to ${\bf 6}$ or ${\bf 6}^*$ of U(3) family symmetry, so that quarks and leptons were not anomaly free in U(3). In this paper, yukawaons are assigned to ${\bf 8}+{\bf 1}$ of U(3), so that quarks and leptons are anomaly free. Since VEV relations among yukawaons are also considerably changed, parameter fitting of the model is renewed. After fixing our free parameters by observed mass ratios, we have only two and one remaining free parameters for quark and lepton mixings, respectively. We obtain successful predictions for the quark and lepton mixing parameters including magnitudes of $CP$ violation. The effective Majorana neutrino mass is also predicted.

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arXiv2013

U(3)$\times$[U(1)]$^3$ Model and Visible Family Gauge Boson Effects

A U(3) family gauge boson model is investigated based on U(3)$\times$[U(1)]$^3$ gauge symmetry. In this model, of nine U(3) family gauge bosons $A_i^{\ j}$, those with $i=j$ are considerable heavy compared with those with $i \neq j$, so that the model can be released from severe constraints due to the observed $K^0$-$\bar{K}^0$ mixing, and so on. We speculate that the lightest gauge boson is $A_2^{\ 3}$ and its mass is of $2 - 6$ TeV. Thereby, visible effects of the family gauge bosons are discussed. Especially, an observation of $μ^- +N \rightarrow e^- + N$ versus no observation of $μ\rightarrow e +γ$ will be a promising test for the present scenario.

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arXiv2013

Neutrino Mass Matrix Model with a Bilinear Form

A neutrino mass matrix model with a bilinear form $M_ν= k_ν(M_D M_R^{-1} M_D^T)^2$ is proposed within the framework of the so-called yukawaon model, which has been proposed for the purpose of a unified description of the lepton mixing matrix $U_{PMNS}$ and the quark mixing matrix $V_{CKM}$. The model has only two adjustable parameters for the PMNS mixing and neutrino mass atios. (Other parameters are fixed from the observed quark and charged lepton mass ratios and the CKM mixing.) The model gives reasonable values $\sin^2 2θ_{12} \simeq 0.85$ and $\sin^2 2θ_{23} \sim 1$ and $\sin^2 2θ_{13} \sim 0.09$ together with $R_ν\equiv Δm^2_{21}/Δm^2_{32} \sim 0.03$. Our prediction of the effective neutrino mass $ $ in the neutrinoless double beta decay takes a sizable value $< m >\simeq 0.0034$ eV.

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arXiv2013

Can Mass of the Lightest Family Gauge Boson be of the Order of TeV?

The observed sign of a deviation from the $e$-$μ$ universality in tau decays suggests family gauge bosons with an inverted mass hierarchy. Under the constraints from the observed $K^0$-$\bar{K}^0$ and $D^0$-$\bar{D}^0$ mixing, we investigate a possibility that a mass $M_{33}$ of the lightest gauge boson $A_3^3$ which couples with only the third generation quarks and leptons is of the order of TeV. It is concluded that $M_{33} \sim 1$ TeV is possible if we adopt a specific model phenomenologically.

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arXiv2013

Large $θ_{13}^ν$ and Unified Description of Quark and Lepton Mixing Matrices

We present a revised version of the so-called "yukawaon model", which was proposed for the purpose of a unified description of the lepton mixing matrix $U_{PMNS}$ and the quark mixing matrix $V_{CKM}$. It is assumed from a phenomenological point of view that the neutrino Dirac mass matrix $M_D$ is given with a somewhat different structure from the charged lepton mass matrix $M_e$, although $M_D=M_e$ was assumed in the previous model. As a result, the revised model predicts a reasonable value $\sin^2 2θ_{13} \sim 0.07$ with keeping successful results for other parameters in $U_{PMNS}$ as well as $V_{CKM}$ and quark and lepton mass ratios.

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arXiv2012

Family Gauge Bosons with an Inverted Mass Hierarchy

A model that gives family gauge bosons with an inverted mass hierarchy is proposed, stimulated by Sumino's cancellation mechanism for the QED radiative correction to the charged lepton masses. The Sumino mechanism cannot straightforwardly be applied to SUSY models because of the non-renormalization theorem. In this talk, an alternative model which is applicable to a SUSY model is proposed. It is essential that family gauge boson masses $m(A_i^j)$ in this model is given by an inverted mass hierarchy $m(A_i^i) \propto 1/\sqrt{m_{ei}}$, in contrast to $m(A_i^i) \propto \sqrt{m_{ei}}$ in the original Sumino model. Phenomenological meaning of the model is also investigated. In particular, we notice a deviation from the $e$-$μ$ universality in the tau decays.

hep-ph↗

arXiv2012

Family Gauge Bosons with an Inverted Mass Hierarchy

A model that gives family gauge bosons with an inverted mass hierarchy is proposed, stimulated by Sumino's cancellation mechanism for the QED radiative correction to the charged lepton masses. The Sumino mechanism cannot straightforwardly be applied to SUSY models because of the non-renormalization theorem. In this paper, an alternative model which is applicable to a SUSY model is proposed. It is essential that family gauge boson masses $m(A_i^j)$ in this model is given by an inverted mass hierarchy $m(A_i^i) \propto 1/\sqrt{m_{ei}}$, in contrast to $m(A_i^i) \propto \sqrt{m_{ei}}$ in the original Sumino model. Phenomenological meaning of the model is also nvestigated. In particular, we notice a deviation from the $e$-$μ$ universality in the tau decays.

hep-ph↗

arXiv2012

Neutrino Mass Matrix with No Adjustable Parameters

On the basis of the so-called "yukawaon" model, we found out a special form of the neutrino mass matrix $M_ν$ which gives reasonable predictions. The $M_ν$ is given by a multiplication form made of charged lepton mass matrix $M_e$ and up-quark mass matrix $M_u$. This $M_ν$ has no adjustable parameters except for those in $M_e$ and $M_u$. Here, $M_e$ and $M_u$ are described by one parameter $a_e$ (real) and two parameters $a_u$ (complex), respectively, and those parameters are constrained by their observed mass ratios. With this form of $M_ν$, in spite of having only three parameters, the $M_ν$ can give reasonable predictions $\sin^2 2θ_{atm} \simeq 0.99$, $\sin^2 2θ_{13} \simeq 0.015$, $Δm^2_{21}/Δm^2_{32} \simeq 0.030$, $< m_{ee}> \simeq 0.0039$ eV, and so on, by using observed values of $m_e/m_μ$, $m_μ/m_τ$, $m_c/m_t$, and $\sin^2 θ_{solar}$ as input values.

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arXiv2012

Yukawaon Model with U(3)$\times$S$_3$ Family Symmetries

A new yukawaon model is investigated under a family symmetry U(3)\times S_3. In this model, all vacuum expectation values (VEVs) of the yukawaons, , are described in terms of a fundamental VEV matrix <Φ_0> as in the previous yukawaon model, but the assignments of quantum number for fields are different from the previous ones: the fundamental yukawaon Φ_0 is assigned to (3,3) of U(3) \times U(3), which is broken into (3,1+2) of U(3) \times S_3, although quarks and leptons are still assigned to triplets of U(3) and yukawaons Y_f are assigned to 6^* of U(3). Then, VEV relations among Yukawaons become more concise considerably than the previous yukawaon models. By adjusting parameters, we can fit not only quark mixing parameters but also lepton mixing parameters together with their mass ratios.

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arXiv2011

SU(5) Compatible Yukawaon Model With Two Family Symmetries U(3)$\times$O(3)

A yukawaon model which is compatible with an SU(5) GUT model is investigated. In a previous SU(5) compatible yukawaon model with a U(3) family gauge symmetry, we could not build a model with a lower energy scale of the family gauge symmetry breaking scale $Λ_{fam}$ than $10^{13}$ GeV, so the family gauge boson effects in the previous model were invisible. In the present model, we consider two family symmetries U(3)$\times$O(3), and we assume that the conventional quarks and leptons $(\bar{\bf 5}+{\bf 10}+{\bf 1})$ of SU(5) are described as $(\bar{\bf 5}_i+{\bf 10}_α+{\bf 1}_α)$ ($ i=1,2,3$ and $α=1,2,3$ are indices of U(3) and O(3), respectively). As a result, we build a model with $Λ_{O3} \sim 10^{16}$ GeV and $Λ_{U3} \sim 10^{3}$ GeV. The lightest U(3) family gauge boson $A_1^1$ will be observed with a mass of the order of 1 TeV.

hep-ph↗

arXiv2011

SU(5)-Compatible Yukawaon Model

It is investigated what constraints are imposed on the so-called yukawaon model when we regard quarks and leptons as $(\bar{\bf 5}_i+{\bf 10}_i+{\bf 1}_i)$ of SU(5) ($i=1,2,3$: index of U(3) family symmetry). In past yukawaon models, the effective Yukawa coupling constants $Y_f^{eff}$ are given by vacuum expectation values of fields $Y_f$ ("yukawaons") as $(Y_f^{eff})_{ij}= (y_f/Λ)<(Y_f)_{ij}>$. In order to build a model without a cutoff scale $Λ$, vector-like fields $(\bar{\bf 5}^i+{\bf 10}^i+{\bf 5}_i +\bar{\bf 10}_i)$ are introduced in addition to the conventional quarks and leptons. The U(3) family symmetry is broken at $ \sim 10^{13}$ GeV.

hep-ph↗

arXiv2011

Yukawaon Model with U(3)$\times$O(3) Family Symmetries

A quark and lepton mass matrix model with family symmetries U(3)$\times$O(3) is investigated on the basis of the so-called yukawaon model. In the present model, quarks and leptons are assigned to $(\ell, e^c, u^c) \sim ({\bf 3}, {\bf 3}, {\bf 3}^*)$ of U(3) and $(q, d^c, ν^c) \sim ({\bf 3}, {\bf 3}, {\bf 3})$ of O(3). Then, the neutrino mass matrix is given by $M_ν= m_D M_R^{-1} m_D^T$ with $m_D \propto < Φ_e > $, where the charged lepton mass matrix $M_e$ is given by $M_e = k < Φ_e ><Φ_e^T >$. A merit in considering U(3)$\times$O(3) lies in that we can lower the cutoff scale $Λ$ in the yukawaon model.

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