Fit of the mixing angles in the six quark model and predictions on theB meson lifetime

Experimental data are used to constrain the parameters of the six quark mixing model and of a composite quark model. A combined fit of the mixing angles in the Kobayashi-Maskawa scheme gives sinθ ₁=0.228±0.011 and error contours around the best values sinθ ₂=0.12 and sinθ ₃≈0. From this, a limit of τ _B >0.35×10^?13 s for the mean lifetime of bottom-flavoured hadrons is obtained. For the composite quark model of Katsumata and Tomozawa, a value of τ _B =(0.22?0.23)10_?13 s is derived.     

Gluon jet in deep inelastic muon scattering

We study the quark and gluon final state in deep inelastic μ-scattering. For a hadron observed at sufficiently large angleθ _h with respect to the virtual photon direction, and sufficiently large energy fractionz _h , this final state dominates the cross-section. Moreover, at the same time, most events in this regime are due to the fragmentation of the quark. In such cases the position of the gluon in phase space is determined, the quark acting as a trigger for gluon jet detection. We demonstrate that in the rest frame of the final quark and gluon, the gluon is energetic and well separated from quark and target fragments. We study the boost from the lab to this frame, and give expressions for the most probable boost in terms ofθ _h andz _h . This study should lead to a convenient visualization of the gluon jet.     

A determination of sin2θ w and the lepton and quark electroweak couplings frome + e − data

Published data on lepton pair and quark pair final states ine ⁺ e ^? annihilation have been analysed in a self consistent way to yield values for the lepton and quark weak vector and axial vector couplings. Generation universality has been tested for the leptons and under the assumption of the standard model of the weak interaction, the parameter sin²θ _w has been determined separately for the lepton and quark sector. In the renormalisation scheme α,G _μ and sin²θ _w , the result for the lepton final states is sin²θ _w = 0.212±0.014 and for the hadron final states, sin²θ _w = 0.236±0.015. The combined result for this single parameter in the model is sin²θ _w = 0.223±0.011±0.007, corresponding tom _Z =93.0 _?1.8 ^+2.0 GeV.     

A new test of CP noninvariance in nonleptonic decay of mesons containing one bottom quark

We show that in six-quark models with a hierarchy of small mixing angles, θ₃ < θ₂ ? 1, and a sizable CP-violating phase δ ～ 1, there is a large difference in the angular distributions, as well as in the rates, when comparing a particular nonleptonic decay mode of a meson containing one bottom quark with the same decay mode of the antiparticle.     

Gluon effects and nonet mixing in the current quark picture

The effects on the meson mass spectrum of gluon interactions, and in particular of quark annihilation diagrams, are investigated in the current quark framework. The resulting mixing scheme leads to mixing angles θp ? ?13° and θ_V ? ? 52° for the pseudoscalar and vector nonets respectively, in moderate agreement with present data on radiative decays. For virtual electromagnetic processes additional gluon diagrams play a role. In η → 3π the net effect is to almost double the current algebra prediction, while in ω → 2π the ω → ?⁰ transition amplitude is correctly predicted in both sign and magnitude. The relation between the Hamiltonian approach and the U(1) problem, as formulated in terms of axial divergences, is briefly discussed.     

Broken collinear SU(6) symmetries and the suppression of |ΔS| = 1 amplitudes

Within the framework of the general mapping between collinear SU(6) algebras in the current- and the constituent-quark picture, a unitary transformation involving the quark mass matrix M = λ₀ + cλ₈ is introduced. It results in a weight factor between ΔS = ± 1 and ΔS = 0 amplitudes. With a specific boundary condition, one obtains tg θ = cos(πc/2√2)θ = Cabibbo angle.     

Radiative transitions of baryons in the MIT bag

Resonance photoproduction is studied via the MIT bag model and comparison is made with a single quark transition SU(6)_θ analysis. Correspondence is found between the two pictures. The bag model predictions are shown to be in good qualitative agreement with experiment; however, specific numerical results are rather model dependent and in general less successful.     

Heavy-quark production at collider energy

The rather large cross section reported for Λ_c production at ISR energy suggests that cross sections for the production of heavier quarks at collider energy could be important. It is then advocated that an interesting kinematical region for the search for leptons associated with t quark formation is p_T > 5 GeV/c, θ ≈ 20–30°.     

The signature of E6 in precision measurements of sin2θw

Precision electroweak experiments can be used to extract three inequivalent values for sin²θ_w. Discrepancies between theses values which cannot be reconciled within the standard model could indicate new physics. In particular, clear signals of the effects of heavy exotic E₆ particles are possible. These effects are easily distinguished from those of a heavy to quark, supersymmetry, or a standard fourth generation.     

Contribution of coloured Higgs bosons to e+e− annihilation into two jets

We examine the effect of the coloured Higgs bosons (of the integer-charge quark model) on electron-positron annihilation into two jets. The overall angular distribution of the quark + gluon + Higgs jets in the scaling limit is found to be 1+0.57 cos²θ.     

y and ν distributions for neutral current reactions of the Weinberg-type

The y and ν distributions for inclusive neutrino and antineutrino reactions arising from a neutral current of the Weinberg-type are investigated in the framework of two quark parton models. While the ν distributions appear of little use at present, we show that by making a cut in the y variable, one can determine sin²θ_W reasonably accurately, independent of the cross section determination, even with the present narrow-band dichromatic neutrino beam at NAL.     

On the determination of sin2θw in semileptonic neutrino interactions

It is shown that if sin²θ_w is measured in semileptonic neutrino interactions then, contrary to a claim in the literature, the error due to unknown dynamical (higher-twist) corrections to the QCD parton model is small provided an isoscalar target is used. The largest contributions to σ_nc and σ_cc are related by isospin invariance alone. Neglecting heavy quarks and Kobayashi-Maskawa (KM) mixing, the parton model is only needed for very small terms and introduces an uncertainty in sin²θ_w which is probably less than 1%. There is a much larger theoretical error due to uncertainties in the element U_cs of the KM matrix and in the strange quark distribution. With the full range 0.80 ? | U_cs | 0.98 which is allowed phenomenologically, these uncetainties give δsin²θ_w = ± 0.008. There is also an error of ±0.004 due to uncertainties in |U_dc| and |U_du|.     

Theta vacuum effects on QCD phase diagram

Theta vacuum effects on the QCD phase structure in the μ-T plane are studied by using the Polyakov-loop extended Nambu-Jona-Lasinio model and its extension, where μ is the quark chemical potential and T is temperature, respectively. As the parameter θ of the theta vacuum increases, the chiral transition becomes stronger. For large θ, it eventually becomes first order even at zero μ.     

The\overline {MS} and on-shell renormalization schemes in the analysis of neutrino scattering experiments

The relationship between the \(\overline {MS} \) and on-shell renormalization schemes is discussed and the correction, for finite top quark mass, to the formula connecting sin² θ _W =1?M _W ² /M _Z ² and sin² \(\widehat\theta _W (M_W )\) is given. A table is presented to allow easy conversion. The relative sensitivity, to the top quark and Higgs masses, of the two definitions, when extracted from semi-leptonic neutrino scattering experiments is considered.     

CP violation and Fritzsch mass matrices

We discuss a form for the quark mass matrices which produces maximal weak but no string CP violation. The quark mass matrices are of the Fritzsch type, with all phases equal to multiples of $\text{1}\text{2}\text{π}$. We show that these matrices can be produced in an SO(10) model with CP violated spontaneously at the GUT scale. The model successfully predicts the entire K-M matrix. Radiative corrections to $\text{θ}$, however, are several orders of magnitude too large in the model, and $\text{θ}$ is naturally of O(10^?5).     

Neutrino masses and mixings based on a special set of quark mass matrices (II)

In the framework of a 6×6 neutrino mass matrix with the standard seesaw mechanism, simple empirical forms are used for the leptonic Dirac mass submatrices which exhibit hierarchical chiral symmetry-breaking structure with just six parameters, as suggested by our previous work with quark mass matrices. Through a Monte Carlo analysis of Euler angle rotations applied to diagonal forms for the right-handed Majorana mass submatrix, we generate scatter plots in the δm ₂₃ ² vs sin²2θ ₂₃ and δm ₁₃ ² vs sin²2θ ₁₃ oscillation planes for a fixed point in the nonadiabatic MSW band. Only a small, statistically insignificant, segment of the 23 mixing plane exists corresponding to depletions of both the solarv _e and atmosphericv _μ fluxes; however, for such solutions the righthanded Majorana submatrix exhibits a hierarchical chiral symmetry-breaking form remarkably similar to that for the Dirac submatrices.     

A determination of quark weak couplings at petra energies

Data on hadron production by e⁺e^? annihilation at c.m. energies between 12 and 36.6 GeV have been collected using the JADE detector. They have been analysed in terms of single-photon and weak neutral-current exchange assuming production of quark-antiquark pairs with only d, u, s, c and b quarks to produce values for the quark weak neutral-current couplings. A further analysis in terms of the Glashow-Salam-Weinberg theory produced the result, sin²θ_{W = 0.22 ± 0.08}. The theory has therefore been tested in a new energy domain and within the context of the neutral weak couplings of the first, second and third generation quarks.     

Configuration Mixing of Quark States in Baryons

Mixing angles are used to describe the SU(6) ? O(3) symmetry breaking in [70, 1^?] multiplet in the sector of the lowest mass nucleon resonances, which are investigated extensively in constituent quark models for baryon spectroscopy. The transition amplitudes for the meson photoproduction off nucleon can also be expressed in terms of the mixing angles to take into account the configuration mixing. Those amplitudes are derived as a function of the mixing angles between ${|N^2P_M{J}^-\rangle}$ and ${|N^4P_M{J}^-\rangle}$ states, with J = 1/2 and 3/2, for the processes γp → ηp, K ⁺ Λ, K ⁺ Σ ^°, K ^° Σ ⁺. The present status of our knowledge on the mixing angles between S ₁₁(1535) and S ₁₁(1650) (θ _S ), as well as between D ₁₃(1520) and D ₁₃(1700) (θ _D ) is reported. Since these resonances play very important role in the threshold region for both η and kaon production mechanisms, they are expected to provide crucial tests of different quark models for the baryon spectroscopy.     

Understanding of radial and elliptic expansion with quark number scaling and blast wave model in 200 GeV Au+Au at RHIC-PHENIX

Measurement of azimuthal anisotropy is one of the most important study because of its relation to the initial stage. Especially, the elliptical anisotropy which is measured as the second coefficient of Fourier expansion of particle azimuthal distribution is believed to carry the information about the initial geometrical anisotropy. It seems the identified hadron v ₂ depends on the number of quark contents of the hadron. The experimental result of quark number scaling of v ₂ suggests quark level collectivity in the hot dense matter and quark coalescence mechanism to form hadron from quark matter via quark-gluon phase transition. The measured v ₂ and p _T spectra are analyzed with various assumptions based on the blast wave model in order to understand the freeze-out temperature and collective flow after the system expansion.