arXiv subjects
Publications and source records attributed to Yoshio Koide.
A compsite model of quarks and leptons is proposed. The quarks and leptons are given by three body states which are composed of constituents $(w_1, w_2, c_1, c_2, c_3)$ of SU(5)$_{flavor}$ and $(f_1, f_2, f_3)$ of SU(3)$_{family}$
We discuss on the search for the right-handed weak interaction effects in the SU(2)$_L \times$SU(2)$_R$ model with lepton doublets $(ν_\ell, \ell^-)_L$ and $(N_\ell, \ell^-)_R$ ($\ell = e, μ, τ)$. We will point out that only the chance of the observation of the right-handed weak interaction effect will be in the rare decay $K^+ \rightarrow π^- μ^+ μ^+$.
Conventionally, the observed charged leptons are regarded the simultaneous eigenstates of "mass" and "family". Against this view, we discuss a possibility that the observed charged leptons $e_i=(e, μ, τ)$ are not identical with the eigenstates of family $e^0_α=(e_1^0, e_2^0, e_3^0)$. Here, we define the eigenstates of family, $e^0_α$, as the states which interact with family gauge bosons in the mass eigenstates of the broken U(3)$_{family}$ gauge symmetry. Although there is at present not any experimental evidence for $e^0_1$-$e^0_2$ mixing, and we have only an upper limit for the mixing from the present experimental data. We will conclude that the $e$-$μ$ mixing angle $θ$ must be $θ\lesssim 10^{-3}$. Thus, we can not exclude a possibility $θ\neq 0$. If we want more small upper limit of $θ$, a rare decay search $μ\rightarrow e + γ$ will be useful.
Stimulated by a successful quark mass matrix model based on U(3)$\times$U(3)$'$ family symmetry, a phenomenological neutrino mass matrix for the Majorana neutrinos $(ν_L, ν_R^c, N_L, N_R^c)$ is proposed. The model has only three adjustable parameters. Nevertheless, the model gives reasonable predictions for the neutrino masses, mixings, and CP violating phases in the neutrino mixing matrix.
The charged lepton mass relation $K \equiv (m_e +m_μ+m_τ)/(\sqrt{m_e} %+\sqrt{m_μ} +\sqrt{m_τ})^2= 2/3 $ is excellently satisfied by observed masses (pole masses). However, the formula $K=2/3$ should be never satisfied with the observed charged lepton masses. We will review a mechanism by proposed by Sumino and recent related topics.
Recently, we have proposed a quark mass matrix model based on U(3)$\times$U(3)$'$ family symmetry, in which up- and down-quark mass matrices $M_u$ and $M_d$ are described only by complex parameters $a_u $ and $a_d $, respectively. When we use charged lepton masses as additional input values, we can successfully obtain predictions for quark masses and Cabibbo-Kobayashi-Maskawa mixing. Since we have only one complex parameter $a_q$ for each mass matrix $M_q$, we can obtain a parameter-independent mass relation by using three equations for ${\rm Tr}[H_q]$, ${\rm Tr}[H_q H_q]$ and ${\rm det}H_q$, where $H_q \equiv M_q M_q^\dagger$ ($q=u, d$). In this paper, we investigate its parameter-independent feature of the quark mass relation in the model.
The observed charged lepton masses satisfy the relations $K \equiv (m_e +m_μ+m_τ)/(\sqrt{m_e} +\sqrt{m_μ} +\sqrt{m_τ})^2 =2/3$ and $κ\equiv \sqrt{m_e m_μm_τ}/(\sqrt{m_e} +\sqrt{m_μ} +\sqrt{m_τ})^3 =1/486$ with great accuracy. These parameters are given as $K=( {\rm Tr}[ΦΦ])/ ({\rm Tr}[Φ])^2$ and $κ= {\rm det} Φ/({\rm Tr}[Φ])^3$ if the charged lepton masses $m_{ei}$ are given by $m_{ei} \propto \sum_k Φ_i^{\ k} Φ_k^{\ i}$ where $Φ$ is a U(3)-family nonet scalar. Simple scalar potential forms to realize the relations have been already proposed in non-supersymmetric scenarios, but the potential forms are not stable against the renormalization group effects. In this paper, we examine supersymmetric scenarios and find that the parameters $K$ and $κ$ are made stable against the effects in a very nontrivial way, even though the superpotential itself (in the canonical basis) suffers the usual corrections. We also show possible simple superpotential forms for the relations.
A charged lepton mass formula $(m_e +m_μ+ m_τ)/(\sqrt{m_e}+\sqrt{m_μ} + \sqrt{m_τ})^2 =2/3$ is well-known. Since we can, in general, have two relations for three quantities, we may also expect another relation for the charged lepton masses. Then, the relation will be expressed by a form of $\sqrt{m_e m_μm_τ}/(\sqrt{m_e}+\sqrt{m_μ} + \sqrt{m_τ})^3$. According to this conjecture, a scalar potential model is speculated.
Recently, Nishiura and the author have proposed a unified quark-lepton mass matrix model under a family symmetry U(3)$\times$U(3)$'$. The model can give excellent parameter-fitting to the observed quark and neutrino data. The model has a reasonable basis as far as the quark sector, but the form of the right-handed neutrino mass matrix $M_R$ does not have a theoretical grand, that is, it was nothing but a phenomenological assumption. In this paper, it is pointed out that the form of $M_R$ is originated in structure of neutrino mass matrix for $(ν_i, N_α)$ where $ν_i$ ($i=1,2,3$) and $N_α$ ($α=1,2,3$) are U(3)-family and U(3)$'$-family triplets, respectively.
We have already proposed a quark and lepton mass matrix model based on U(3)$\times$U(3)$'$ family symmetry as the so-called Yukawaon model, in which the U(3) symmetry is broken by VEVs of flavons $(Φ_f)_i^{\ α}$ which are $({\bf 3}, {\bf 3}^*)$ of U(3)$\times$U(3)$'$. The model has successfully provided the unified description of quark and lepton masses and mixings by using the observed charged lepton masses as only family-number dependent input parameters. Our next concern is scales of VEVs of the flavons. In the present paper, we estimate the magnitudes of the VEV scales of flavons of the model which is newly reconstructed without changing the previous phenomenological success of parameter fitting for masses and mixings of quarks and leptons. We estimate that VEVs of flavons with $({\bf 8+1}, {\bf 1})$, $({\bf 3}, {\bf 3}^*)$, and $({\bf 1}, {\bf 8+1})$ are of 25the orders of $10$ TeV, $10^4$ TeV, and $10^7$ TeV, respectively.
An interesting family gauge boson (FGB) model (Model A) has been proposed by Sumino. The model can give FGBs with a considerably low energy scale in spite of the sever constraints form the observed $K^0$-$\bar{K}^0$ mixing and so on. An essential idea in Model A is in the so-called Sumino cancellation mechanism between QED and FGB diagrams. However, Model A is not anomaly free and, besides, it causes effective interactions with $ΔN_{\rm family}=2$. In order to avoid these problems, a revised Sumino model with an inverted mass hierarchy (Model B) has proposed, but, in this time, it cannot satisfy the Sumino cancellation mechanism exactly. In this paper, we propose a revised version of Model B, where the model still keeps anomaly free, but it can exactly satisfy the Sumino mechanism. An effect of the revised model will be confirmed by observations $K^+ \rightarrow π^+ e^- μ^+$ and $μ^- N\rightarrow e^- N$.
There are two formulas for charged lepton mass relation: One is a formula (formula A) which was proposed based on a U(3) family model on 1982. The formula A will be satisfied only masses switched off all interactions except for U(3) family interactions. Other one (formula B) is an empirical formula which we have recognized after a report of the precise measurement of tau lepton mass, 1992. The formula B is excellently satisfied by pole masses of the charged leptons. However, this excellent agreement may be an accidental coincidence. Nevertheless, 2009, Sumino has paid attention to the formula B. He has proposed a family gauge boson model and thereby he has tried to understand why the formula B is so well satisfied with pole masses. In this talk, the following views are given: (i) What direction of flavor physics research is suggested by the formula A; (ii) How the Sumino model is misunderstood by people and what we should learn from his model; (iii) What is strategy of my recent work, U(3)$\times$U(3)$'$ model.
We study the $μ$-$e$ conversion in muonic atoms via an exchange of family gauge boson (FGB) $A_{2}^{\ 1}$ in a $U(3)$ FGB model. Within the class of FGB model, we consider three types of family-number assignments for quarks. We evaluate the $μ$-$e$ conversion rate for various target nuclei, and find that next generation $μ$-$e$ conversion search experiments can cover entire energy scale of the model for all of types of the quark family-number assignments. We show that the conversion rate in the model is so sensitive to up- and down-quark mixing matrices, $U^{u}$ and $U^{d}$, where the CKM matrix is given by $V_\text{CKM} = U^{u\dagger} U^d$. Precise measurements of conversion rates for various target nuclei can identify not only the types of quark family-number assignments, but also each quark mixing matrix individually.
Recently, we proposed a unified mass matrix model for quarks and leptons, in which, mass ratios and mixings of the quarks and neutrinos are described by using only the observed charged lepton mass values as family-number-dependent parameters and only six family-number-independent free parameters. In spite of quite few parameters, the model gives remarkable agreement with observed data (i.e. CKM mixing, PMNS mixing and mass ratios). Taking this phenomenological success seriously, we give a formulation of the so-called Yukawaon model in details from a theoretical aspect, especially for the construction of superpotentials and $R$ charge assignments of fields. The model is considerably modified from the previous one, while the phenomenological success is kept unchanged.
We propose a unified mass matrix model for quarks and leptons, in which sixteen observables of mass ratios and mixings of the quarks and neutrinos are described by using no family number-dependent parameters except for the charged lepton masses and only six family number-independent free parameters. The model is constructed by extending the so-called "Yukawaon" model to a seesaw type model with the smallest number of possible family number-independent free parameters. As a result, once the six parameters is fixed by the quark mixing and the mass ratios of quarks and neutrinos, no free parameters are left in the lepton mixing matrix. The results are in excellent agreement with the neutrino mixing data. We predict $δ_{CP}^\ell =-68^\circ$ for the leptonic $CP$ violating phase and $\langle m\rangle\simeq 21$ meV for the effective Majorana neutrino mass.
It is emphasized that a rare decay $K^+ \rightarrow π^+ ν\barν$ becomes promising in a future search for a new particle, because the theoretical treatment is well established and the value of the branching ratio $Br(K^+ \rightarrow π^+ ν\barν)$ is sensitive to a search for a new particle with a TeV scale mass. As an example, according to a U(3) family gauge boson model which predicts the lowest family gauge boson with a few TeV mass $M_{11}$, the branching ratio $Br(K^+ \rightarrow π^+ ν\barν)$ is discussed. If we can obtain, in future, a slightly lower value $Br^{obs} \sim 0.9 \times 10^{-10}$ compared with the present observed value $Br^{obs}=(1.7\pm 1.1)\times 10^{-10}$, we can conclude $M_{11} \sim$ a few TeV.
Family gauge boson production at the LHC is investigated according to a $U(3)$ family gauge model with twisted family number assignment. In the model we study, a family gauge boson with the lowest mass, $A_1^{\ 1}$, interacts only with the first generation leptons and the third generation quarks. (The family numbers are assigned, for example, as $(e_1, e_2, e_3)= (e^-, μ^-, τ^-)$ and $(d_1, d_2, d_3)=(b, d, s) $[or $(d_1, d_2, d_3)=(b, s, d)$]). In the model, the family gauge coupling constant is fixed by relating to the electroweak gauge coupling constant. Thus measurements of production cross sections and branching ratios of $A_1^{\ 1}$ clearly confirm or rule out the model. We calculate the cross sections of inclusive $A_1^{\ 1}$ production and $b \bar{b} \, (t \bar{t})$ associated $A_1^{\ 1}$ production at $\sqrt{s} = 14~\text{TeV}$ and $100~\text{TeV}$. With the dielectron production cross section, we discuss the determination of diagonalizing matrix of quark mass matrix, $U_{u}$ and $U_{d}$, respectively.
It is investigated whether observations of family gauge bosons by terrestrial experiments are possible or not. We propose an extended version of Sumino's family gauge boson model based on U(3) family symmetry. Then, we can expect the lowest family gauge boson $A_1^1$ with $M \sim 4.3$ TeV.