Symmetric six-quark model and associated neutral currents

A symmetric six-quark gauge model is proposed to account for the recent neutrino and antineutrino data on charged and neutral currents. As a bonus, exact isospin symmetry for strong interaction is obtained in a natural way. Further consequences are elaborated.     

Radiative decays as a test for right-handed currents

It is shown that the purity violating amplitude for the decays Σ⁺ → pγ and Ξ^? → Σ^?γ vanish in the SU(3) symmetry limit if the charged weak currents possess a U spin symmetry for strangeness changing processes. This applies to Cabibbo currents and their SU (4) generalization. Assuming an asymptotically free model for the strong interactions this result applies to all models with only left-handed charged currents. Observation of a large parity violating amplitude would indicate right-handed charged weak currents. Tests involving other radiative decays are also considered.     

Charmed meson decays and right-handed currents

In the presence of right-handed currents including $\text{(}\text{c}\text{s}\text{)}{}_{\mathrm{<mtext>R</mtext>}}$, it is emphasized that the dominant parity-violating (-conserving) Hamiltonian for nonleptonic decays of charmed hadrons transforms like $\text{45}\text{+}\text{45}{}^1\text{(}\text{20″ +}\text{84}\text{)}$ of SU(4), and leads to distinctive results especially in D⁺ → K_Sπ⁺, F⁺ → μ⁺ν_μ and D⁰ → K^?e⁺ν_e, etc.     

Parameters of the six-quark model

The restrictions imposed on the parameters of the six-quark model by the neutral kaon system are discussed with QCD effects included in the leading logarithmic approximation. The dependence on the six-quark model parameters of the sign and magnitude of the CP violation parameter ε′, the b-quark lifetime and the ratio of decay widths $\text{Γ(b → uX)}\text{Γ(b → cX)}$ are also discussed.     

NN potential with a six-quark core from the constituent quark model

A mesonic nucleon-nucleon potential from an effective quark interchange mechanism for non-overlapping nucleons is obtained from the constituent quark model. This is supplemented at short range by a phenomenological, non-mesonic potential describing the transition to a six-quark core with a discrete energy spectrum. NN phase shifts and low energy parameters are calculated and compared with data and phase shift analyses. Core parameters are extracted from the fits.     

Parity conserving neutral currents and right-handed neutrinos

Interpreting the leptons as a fourth color degree of freedom, we study a unique theory of the weak and electromagnetic interactions involving two neutral massive intermediate bosons. The neutral current interaction conserves parity. Implications of a university of weak, electromagnetic and strong interactions are discussed.     

Search for right-handed currents in muon decay

We report new limits on right-handed currents, based on precise measurements of the endpoint of the e⁺ spectrum from ⁺ decay. Highly polarized ⁺ from the TRIUMF surface beam were stopped in pure metal foils within either an 1.1-T spin-holding logitudinal field, or a 70-gauss spin-precessing transverse field. Decay e⁺ emitted within 200 mrad of the beam direction were momentum-analyzed to ±0.2%. For the spin-held data, decay via (V-A) currents requires the e⁺ rate to approach zero in the beam direction at the endpoint. Measurement of this rate sets the 90%-confidence limits P />0.9959 and M(W_R)>380 GeV, where W_R is the possible right-handed gauge boson. For the spin-precessed data we independently determine a 90% confidence limit P />0.9918.We are indebted to the entire TRIUMF management and staff for their splendid support of this experiment. In its early stages we benefited from discussion with J. Brewer, R. Cahn, K. Crowe, and W. Wenzel. Rapid commissioning of the polarimeter was made possible by the superb efforts of the LBL support staff. This research was supported in part by the U.S. Department of Energy, Division of Basic Energy Sciences, Office of Energy Research under contracts W-7405-ENG-48 and AC02-ER02289.     

A new unified theory with right-handed currents and proton stability

A unified vector-like gauge theory based on SU(6) is proposed, where the proton stability is achieved with reasonable lepto-quark massemeasurable in the decay K_L⁰→μe. We predict the existence of a long-lived messon decaying into Pe^?.     

Test of right-handed currents in baryon semileptonic decays

The effect of a right-handed boson on baryon semileptonic decay is considered. The analysis of polarized and unpolarized decays is carried out and it is shown that the best place to look for a right-handed current (RHC) signature is in polarized baryon decay. However, our results are useful for high statistics experiments. In order to see the contribution of the right-handed currents in the case of unpolarized hyperon decay, the Cabibbo theory should be assumed.     

Charged current couplings in the six-quark model

New values for the V_cd and V_cs couplings are determined from opposite sign dimuon data. These results together with the V_ud and V_us couplings give restrictive bounds for other elements of the Kobayashi-Maskawa matrix.     

Symmetries of the standard model without and with a right-handed neutrino

Given the particle content of the standard model without and with a right-handed neutrino, the requirement that all anomalies cancel singles out a set of possible global symmetries which can be gauged. I review this topic and propose a new gauge symmetryB — 3L _T in the context of the minimal standard model consisting of the usual three families of quarks and leptons plus just onev _R. The many interesting phenomenological consequences of this hypothesis are briefly discussed.     

Quark masses and flavor-mixing angles in a six-quark model of quantum flavordynamics

The Cabibbo-like flavor-mixing angles are related to quark masses through spontaneous symmetry breaking in an illustrative model of quantum flavordynamics based on the SU_2L x SU_2R x U₁ flavor gauge group and on six quark flavors. Theoretical and experimental consequences of the scheme are discussed.     

Neutral mesons with heavy quarks and mixing angles in the six-quark model

In the framework of the six-quark model, based on the gauge group SU(2)_L × U(1) we have obtained expressions for the amplitudes of $\text{K}{}^0\text{?}\text{K}{}^0\text{,}\text{D}{}^0\text{?}\text{D}{}^0\text{,}\text{B}{}^0\text{?}\text{B}\text{B}{}_{\mathrm{S}}{}^0\text{?}\text{B}{}_{\mathrm{S}}{}^0\text{,}\text{T}{}^0\text{?}\text{T}{}^0\text{and}\text{T}{}_{\mathrm{c}}{}^0\text{?}\text{T}{}_{\mathrm{C}}{}^0$ transitions at final 4-momenta of external lines Feynman box diagrams. We have estimated the correctness of using the approximation of extremely small 4-,omenta of valence quarks, composing K⁰-like mesons. The constraints for the parameters of the unitary matrix of weak charged currents have been found at arbitrary value of the t-quark mass. Estimates of numerical values for the mixing parameters and for the parameters of CP violation for neutral systems similar to $\text{K}{}^0\text{?}\text{K}{}^0$ are given.     

Properties of six-quark clusters in the topological chiral soliton model

The energy and bag radius of a six-quark configuration are obtained from a topological chiral soliton model. The calculation shows that three and six quark systems in this model behave much as those in the MIT bag model.     

Off-shell behaviour of theN-N interaction in a six-quark resonating group model of the deuteron

Two different 6-quark resonating group models of the deuteron are investigated to study the off-shell property of theN-N interaction. In the first model the quarks interact by a central one-gluon-exchange potential plus confinement potential. The meson-exchange contribution to then-p potential is simulated by a central GaussianN-N potential. In the second model the quarks interact by one-gluon-and one-pion-exchange potentials (central and noncentral) plus confinement potential. A small additional -exchange potential between neutron and proton binds the deuteron at the correct energy.Several off-shell variants of the two resonating group models are compared with each other by analyzing their elastic electron scattering cross sections. It is found that the standard renormalized version of the resonating group model yields potentials and wave functions that may be considered physical within the limitations of the model. Unitary off-shell transformations, which modify potentials and wave functions in any sizeable way, lead to a disagreement between the charge distribution predicted by the model via analysis of electron scattering and the charge distribution following from the microscopic quark distribution.Both of the 6-quark models support a soft repulsive core of the tripletn-p potential with a core height of around 900 MeV.