arXiv subjects
Publications and source records attributed to Shinya Matsuzaki.
Using the binary tetrahedral group $T^{'}$, the three angles and phase of the quark CKM mixing matrix are pursued by symmetry-breaking which involves $T^{'}$-doublet VEVs and the Chen-Mahanthappa CP-violation mechanism. The NMRT$^{'}$M, Next-to-Minimal-Renormalizable -T$^{'}$-Model is described, and its one parameter comparison to experimental data is explored.
Generalizing a previous model to accommodate the third quark family and CP violation, we present a $T^{'}$ model which predicts tribimaximal neutrino (PMNS) mixings while the central predictions for quark mixings are $|V_{td}/V_{ts}| = 0.245$ and $|V_{ub}/V_{cb}| = 0.237$ with a predicted CP violating KM phase $δ_{KM} = 65.8^{0}$. All these are acceptably close to experiment, including the KM phase for which the allowed values are $63^{0} < δ_{KM} < 72^{0}$, and depend only on use of symmetry $T^{'} \times Z_2$ to define the model and no additional parameters.
It is shown that the ratio of branching ratios in Higgs boson decay $r = Γ(H \to τ^+τ^-)/Γ(H\to μ^+μ^-)$ in a simplified ($T^{'} \times Z_2$) model is $(r)_{T^{'} \times Z_2} \simeq 0.001$. This prediction is on a footing with the successful one in $(s, d)$ mixing, $\tan 2 Θ_{12} = {1/3}(\sqrt{2})$. This value for $r$ differs from that of the minimal standard model by a very large factor (over 250,000) and can provide a smoking gun for ($T^{'} \times Z_2$) flavor symmetry.
In this note we compute the flavor-dependent chiral-logarithmic corrections to the decay Z to b bbar in the three site Higgsless model. We compute these corrections diagrammatically in the "gaugeless" limit in which the electroweak couplings vanish. We also compute the chiral-logarithmic corrections to the decay Z to b bbar using an RGE analysis in effective field theory, and show that the results agree. In the process of this computation, we compute the form of the chiral current in the gaugeless limit of the three-site model, and consider the generalization to the N-site case. We elucidate the Ward-Takahashi identities which underlie the gaugeless limit calculation in the three-site model, and describe how the result for the Z to b bbar amplitude is obtained in unitary gauge in the full theory. We find that the phenomenological constraints on the three-site Higgsless model arising from measurements of Z to b bbar are relatively mild, requiring only that the heavy Dirac fermion be heavier than 1 TeV or so, and are satisfied automatically in the range of parameters allowed by other precision electroweak data.
Flavor symmetry ($T^{'} \times Z_2$) where $T^{'}$ is the binary tetrahedral group predicts for neutrino mixing angles $θ_{13} = \sqrt{2} (\fracπ{4} - θ_{23})$ and, with one phenomenological input, provides upper and lower bounds on both $θ_{13}$ and $θ_{23}$. The predictions arise from the deviation of the Cabibbo angle $Θ_{12}$ from its lowest-order value $\tan 2Θ_{12} = (\sqrt{2})/3$ and from the $T^{'}$ mechanism which relates mixing of $(ν_τ, ν_μ, ν_e)$ neutrinos to mixing of $(s, d)$ quarks.
We revisit $A_4$ flavor symmetry for the lepton sector with minimal Higgs sector, namely just one $A_4-$triplet SU(2)-doublet scalar. To increase predictivity even further, we impose the constraint of renormalizability. A geometric interpretation of an $A_4-$triplet aids our understanding of tribimaximal mixing. To increase predictivity even further, we impose the constraint of renormalizability. We investigate the neutrino mass hierarchy in such a minimal $A_4$ model and find there are two solutions: one with $m_2 \gg m_1 = m_3$ is phenomenologically unacceptable; the other with $m_3 \gg m_1 = m_2$ is a normal hierarchy. An inverted hierarchy is impossible without addition of more parameters by either more Higgs scalars or higher-order irrelevant operators.
In a simplified renormalizable model where the neutrinos have PMNS (Pontecorvo-Maki-Nakagawa-Sakata) mixings tan$^{2} θ_{12} = {1/2}, θ_{13}=0, θ_{23} = π/4$ and with flavor symmetry $T^{'}$ there is a corresponding prediction where the quarks have CKM (Cabibbo-Kobayashi-Maskawa) mixings tan$2 Θ_{12} = \frac{\sqrt{2}}{3}, Θ_{13}=0, Θ_{23} =0$.
We explicitly calculate the $S$ parameter in entire parameter space of the holographic walking/conformal technicolor (W/C TC), based on the deformation of the holographic QCD by varying the anomalous dimension from $γ_m \simeq 0$ through $γ_m \simeq 1$ continuously. The $S$ parameter is given as a positive monotonic function of $ξ$ which is fairly insensitive to $γ_m$ and continuously vanishes as $S \sim ξ^2 \to 0$ when $ξ\to 0$, where $ξ$ is the vacuum expectation value of the bulk scalar field at the infrared boundary of the 5th dimension $z=z_m$ and is related to the mass of (techni-) $ρ$ meson ($M_ρ$) and the decay constant ($f_π$) as $ξ\sim f_πz_m \sim f_π/M_ρ$ for $ξ\ll 1$. However, although $ξ$ is related to the techni-fermion condensate $\condense$, we find no particular suppression of $ξ$ and hence of $S$ due to large $γ_m$, based on the correct identification of the renormalization-point dependence of $\condense$ in contrast to the literature. Then we argue possible behaviors of $f_π/M_ρ$ as $\condense \to 0$ near the conformal window characterized by the Banks-Zaks infrared fixed point in more explicit dynamics with $γ_m \simeq 1$. It is a curious coincidence that the result from ladder Schwinger-Dyson and Bethe-Salpeter equations well fits in the parameter space obtained in this paper. When $f_π/M_ρ\to 0$ is realized, the holography suggests a novel possibility that $f_π$ vanishes much faster than the dynamical mass $m$ does.
We complete the list of one loop renormalization group equations and matching conditions relevant for the computation of the electroweak precision parameters $S$ and $T$ in the three site Higgsless model. We obtain one-loop formulas for $S$ and $T$ expressed in terms of physical observables such as the KK gauge boson mass $M_{W'}$, the KK fermion mass $M$, and the KK gauge boson ($W'$) couplings with light quarks and leptons $g_{W'ff}$. It is shown that these physical observables, $M_{W'}$, $M$ and $g_{W'ff}$ are severely constrained by the electroweak precision data. Unlike the tree level analysis on the ideally delocalized fermion, we find that perfect fermiophobity of $W'$ is ruled out by the precision data. We also study the cutoff dependence of our analysis. Although the model is non-renormalizable, the dependence on the cutoff parameter $Λ$ is shown to be non-significant.
Although tribimaximal mixing (TBM) and quark-lepton complementarity (QLC) are both compatible with experimental data within one standard deviation ($ 1 σ$), the TBM and QLC assumptions are mutually exclusive by $56 σ$.
Spontaneously broken flavor symmetry involving the binary tetrahedral group $T^{'}$ relates parameters in the standard model. In one example the CP violating Pontecorvo-Maki-Nakagawa-Sakata phase $δ_{PMNS}$ and atmospheric mixing angle $θ_{23}$ of neutrinos are related to the Cabibbo mixing angle $Θ_C$ for quarks. A second formula relates a ratio of neutrino mass eigenvalues to the Cabibbo angle.
A systematic study of the flavor group $T^{'}$ is presented in terms of a specific model which extends the standard model symmetry to $[SU(3) \times SU(2) \times U(1)]_{(local)} \times [T^{'} \times Z_2 \times Z_2^{'} \times Z_2^{''}]_{(global)}$. In the model, approximate tribimaximal mixing occurs in the neutrino sector. There is also one new formula relating a quark mixing parameter to quark masses. Most exciting are new formulas relating lepton and quark mixing parameters of the type usually associated with grand unification but here relying only on the group structure of $T^{'}$. Flavor-changing neutral currents in the model lead to lower bounds on scalar masses.
Inspired by the Landau two-fluid model of superfluidity, we consider a similar multifluid description for cosmology where two normal fluids occur for matter and radiation respectively. For cyclic cosmology, two dark energy superfluid components turn out to be insufficient but three superfluids can lead to a sensible five-fluid model which in a certain limit becomes indistinguishable from the brane-world cyclic model proposed earlier (Baum and Frampton). Distinguishing more general five-fluid models from brane-world models for cyclic cosmology could be feasible with more accurate observational data.
In cyclic cosmology based on phantom dark energy the requirement that our universe satisfy a CBE-condition ({\it Comes Back Empty}) imposes a lower bound on the number $N_{\rm cp}$ of causal patches which separate just prior to turnaround. This bound depends on the dark energy equation of state $w = p/ρ= -1 - ϕ$ with $ϕ> 0$. More accurate measurement of $ϕ$ will constrain $N_{\rm cp}$. The critical density $ρ_c$ in the model has a lower bound $ρ_c \ge (10^9 {\rm GeV})^4$ or $ρ_c \ge (10^{18} {\rm GeV})^4$ when the smallest bound state has size $10^{-15}$m, or $10^{-35}$m, respectively.
In this paper we compute the one-loop chiral logarithmic corrections to all O(p^4) counterterms in the three site Higgsless model. The calculation is performed using the background field method for both the chiral- and gauge-fields, and using Landau gauge for the quantum fluctuations of the gauge fields. The results agree with our previous calculations of the chiral-logarithmic corrections to the S and T parameters in 't Hooft-Feynman gauge. The work reported here includes a complete evaluation of all one-loop divergences in an SU(2) x U(1) nonlinear sigma model, corresponding to an electroweak effective Lagrangian in the absence of custodial symmetry.
In this paper we compute the the one-loop chiral logarithmic corrections to the S and T parameters in a highly deconstructed Higgsless model with only three sites. In addition to the electroweak gauge bosons, this model contains a single extra triplet of vector states (which we denote ρ^{\pm} and ρ^0), rather than an infinite tower of "KK" modes. We compute the corrections to S and T in 'tHooft-Feynman gauge, including the ghost, unphysical Goldstone-boson, and appropriate "pinch" contributions required to obtain gauge-invariant results for the one-loop self-energy functions. We demonstrate that the chiral-logarithmic corrections naturally separate into two parts, a model-independent part arising from scaling below the ρmass, which has the same form as the large Higgs-mass dependence of the S or T parameter in the standard model, and a second model-dependent contribution arising from scaling between the ρmass and the cutoff of the model. The form of the universal part of the one-loop result allows us to correctly interpret the phenomenologically derived limits on the S and T parameters (which depend on a "reference" Higgs-boson mass) in this three-site Higgsless model. Higgsless models may be viewed as dual to models of dynamical symmetry breaking akin to "walking technicolor", and in these terms our calculation is the first to compute the subleading 1/N corrections to the S and T parameters. We also discuss the reduction of the model to the ``two-site'' model, which is the usual electroweak chiral lagrangian, noting the ``non-decoupling'' contributions present in the limit as M_ρgoes to infinity.
These results have been incorporated into an expanded version of hep-ph/0607191 that discusses both the S and T parameters in the three site Higgless model.