On the λλ spectroscopy in e+e− annihilation

The properties of the radial excitations of the ?, ω and ? mesons are discussed. In particular it is proposed to identify the recently observed states at √s ? 1.5, 1.82 and 2.13 GeV in e⁺e^? annihilation with the $\text{?}{}_{\mathrm{<mtext>D</mtext>}}\text{≡}{}^3\text{D}{}_1\text{(λλ), ?″}\text{and}\text{?′″}$ mesons respectively. The ?′ meson is suggested to lie in the vicinity of 1.5 GeV and strongly coupled to the ?_D. The ?″(1.6) width is also suggested to be smaller than previously reported.     

The mixing and decays of isoscalar mesons

The predictions of a linear mass mixing model for pseudoscalar and vector mesons, which incorporates the effects of radial excitations, are examined. Several analyses are made fitting in each case to a different experimental value of $\text{Γ(ψ →η'γ)}\text{Γ(ψ→ηγ)}$ upon which the η-η′ mixing pattern is very sensitive. Predictions for radiative transitions among the mesons and for the ratio of production amplitudes $\text{σ}\text{(π}{}^{\mathrm{?}}\text{p→η′n)}\text{σ}\text{(π}{}^{\mathrm{?}}\text{p→ηn)}$ are compared with experiments. Results indicate a preferred value of 3.1 for $\text{Γ(ψ→η′γ)}\text{Γ(ψ→ηγ)}$.     

Electromagnetic mass differences of the old and the charmed mesons

We predict for M_?⁺?M_?⁰ the values -3.4 ± 0.8 MeV using the ?-ω mixing and the quark model, respectively. The extracted parameters indicate the necessity of a relativistic treatment of the old mesons. The problem of extrapolating these parameters to the charmed mesons is discussed. Under conservative assumptions, we predict 1.7 ? M_D⁰ ? 2.2 MeV and .     

A relativistic quark model for mesons based on numerical solutions of the Bethe-Salpeter equation

A study is made to determine if the results of the nonrelativistic quark model can be reproduced by a fully relativistic model of deeply bound $\text{spin}\text{-}\text{1}\text{2}$ quarks. It is found that the relativistic model does not reproduce the nonrelativistic results, even when the quarks have nonrelativistic momenta. However, the model is rather successful in accounting for the known properties of mesons.Numerical solutions to the Bethe-Salpeter equation are obtained for pseudoscalar and vector bound states of equal mass quark-antiquark pairs, with either a scalar, pseudoscalar, or neutral vector exchange interaction. The interaction function corresponds to single particle exchange, with the addition of either one or two regulating terms. It is found that the second regulator allows the internal quark momentum to be nonrelativistic, but that the spinor structure of the wave function remains highly relativistic.Only the scalar interaction can account for the observed spectrum of states. The pseudoscalar interaction yields a vector state of lower mass than the pseudoscalar state, and the vector interaction leads to a vector state which lies approximately one quark mass above the pseudoscalar state. The λ quark is taken as slightly heavier than the p and n, and the perturbation treatment of the mass difference leads to a quadratic mass formula.The decay amplitudes for π, K → μν are calculated, and it is found, independent of parameters, that $\text{?}{}_{\mathrm{\pi }}\text{≈ ?}{}_{\mathrm{K}}$ for either a scalar or vector interaction, in agreement with experiment and in contrast with the nonrelativistic model. The amplitudes for ?^o, ω, φ → e⁺e^?, μ⁺μ^? are also calculated, but in this case the ratios (again parameter independent) are in minor discrepancy with experiment.The question of the additivity of quark amplitudes is examined by calculating (with significant restrictions) the magnetic moments of the vector mesons and the amplitudes for magnetic transitions such as ω → π^oγ. The magnetic moments of the vector mesons have the same (trivial) ratios to each other as in the nonrelativistic model, but they are strongly enhanced over the sum of the quark magnetic moments. The amplitude for magnetic transitions, however, is related to the quark magnetic moments in approximately the same ratio as in the nonrelativistic model.The model is also used to obtain parameter dependent predictions for the masses and decay amplitudes. These predictions are not experimentally correct, but are generally well within an order of magnitude for a wide range of the parameters.The most significant defect discovered of the model is the presence of ghost states (the daughters of the vector mesons, with J^PC = 0^+?) with masses of about 2 BeV.     

Upper limits for charm production in 150 GeV p-Be interactions

A search has been made for the hadronic production of charmed baryons and mesons with a large aperture forward magnetic spectrometer using 150 GeV protons originating from the CERN-SPS. A prompt electron trigger was used as a signature for charm. Upper limits at 90% confidence level have been obtained for the production of $\text{Λ}{}_{\mathrm{<mtext>c</mtext>}}{}^{\mathrm{+}}\text{D}{}^0\text{,}\text{D}{}^0\text{D}{}^{\mathrm{+}}\text{and D}{}^{\mathrm{?}}\text{: σ(Λ}{}_{\mathrm{<mtext>c</mtext>}}\text{) ? 8 μ}\text{b}\text{, σ(}\text{D}{}^0\text{) ? 64 μ}\text{b}\text{, σ(}\text{D}{}^0\text{) < 37 μ}\text{b}\text{, σ(}\text{D}{}^{\mathrm{+}}\text{) ? 51 μ}\text{b and}\text{σ(}\text{D}{}^{\mathrm{?}}\text{) ? 49 μ}\text{b}$ per nucleon, assuming linear A dependence. Systematic errors due to uncertainties in branching ratios and to model dependence of the acceptance calculation are discussed.     

Meson decay constants and bare quark masses from duality for current two-point functions

Duality is applied in a quasi-local form to the SU(4) × SU(4) current two-point functions. Interpolating functions for some of their space-time components are assumed to be given by the free quark model. Mass intervals in the finite energy sum rules are taken to be approximately SU(3) × SU(3) invariant and a linear dependence of the hadronic mass spectrum upon the radial quantum number is assumed. The correct order of magnitude of various meson decay constants is reproduced provided the color gauge group is SU(3). The bare uncharmed quark masses are given by the formulae: $\text{m}{}_{\mathrm{<mtext>u</mtext>}}\text{≌ M}{}_{\mathrm{\pi }}\text{F}{}_{\mathrm{\pi }}\text{/F}{}_{\mathrm{\pi }}\text{√6 ≌ 40}\text{MeV}\text{, m}{}_{\mathrm{<mtext>s</mtext>}}\text{/m}{}_{\mathrm{<mtext>u</mtext>}}\text{≌ 1 = 6}$. The η-η mixing problem is discussed. Predictions are made for the masses and decay constants of the vector mesons of the first L = 2 level of SU(6) × O(3), as well as for the decay constants of the radially excited pseudoscalar mesons; estimates of corrections to PCAC in Goldberger-Treiman relations are presented. The bare charmed quark mass is found to be of the order of 1.1–1.2 GeV. Some decay constants of charmed mesons are evaluated.     

P-wave radial mixing in mesons

Mixings between P-wave mesons and their radial excitations are shown to have a significant effect on standard evaluations of E1 radiative decays. The mixings, which are naturally induced by the one-gluon-exchange Fermi-Breit hamiltonian, also improve the predicted P-wave charmonium masses. Width calculations are performed for charmonium states and the usual prediction of $\text{Г(ψ′→}{}^3\text{P}{}_{\mathrm{0\gamma }}\text{)=40–50 KeV}$, for example, is reduced by a factor of two. Agreement with experiment is considerably improved.     

SU(6) × SL(3, R) color quark model

A nonrelativistic color quark model based on the spectrum generating group SU(6)×SL(3, R) is presented. The model unifies SU(6) and the Regge classification with linear L vs m² mass spectrum. Baryons are predicted to belong to the ($\text{56}\text{, L}{}^{\mathrm{P}}\text{= (}\text{even}{}^{\mathrm{+}}\text{)}\text{and}\text{(}\text{70}\text{, L}{}^{\mathrm{P}}\text{= (}\text{odd}{}^{\mathrm{?}}\text{)}$ multiplets of the SU (6) × O(3) group.     

Predictions of duality for the charmed meson masses

The constraints of duality via FESR's are applied to the processes P+P→P+V, using particles with a new quantum number (charm) as both external and internal (resonance saturation) states. The results are independent of any detailed dynamics or symmetry schemes, as well as independent of coupling strengths. We use the masses of the recently-discovered D and D¹ to set the scale. We predict , m_F = 1938 ± 33 MeV, . Thus slopes of Regge trajectories for charmed mesons are predicted to be substantially smaller than those for ordinary mesons.     

Five quarks,new particles and V + A currents

We propose an SU(5) model for the new heavy mesons, with a charge $\text{?1}\text{3}$ fancy quark in addition to a charge $\text{+2}\text{3}$ charmed quark. Besides interpreting the two narrow vector mesons J/Ψ and Ψ′ as c$\text{c}$ and f$\text{f}$ bound states and accounting for present data in a natural way, the model has (i) three new fancy vector mesons in addition to the charmed ones of the SU (4) model, (ii) at most two new $\text{C = P = +}\text{mesons}\text{(}\text{c}\text{c}\text{,}{}^3\text{P}{}_{\mathrm{J}}\text{, J = 0, 1)}$ between J/Ψ and Ψ ′, with suppressed radiative decays $\text{Ψ′ →}{}^3\text{P}{}_{\mathrm{J}}\text{+ γ}$, (iii) a state near 4.6 GeV in e⁺e^?, decaying mostly to fancy mesons if it is broad or perhaps charmed mesons if it is narrow, (iv) V + A weak currents and a large anomaly in $\text{ν}$N reactions, (v) a possible heavy lepton.     

Thermodynamical analysis of the EMC effect

Assuming that the sea quark distribution vanishes for x > 0.3, we analyse the F₂^Fe(x, Q²) and F₂^D(x, Q²) structure functions measured by the European Muon Collaboration in the framework of a thermodynamical model of the valence quarks. The experimental ratio $\text{F}{}_2{}^{\mathrm{<mtext>Fe</mtext>}}\text{(x)}\text{F}{}_2{}^{\mathrm{<mtext>D</mtext>}}\text{(x)}$ is well reproduced over the whole x range by the ratio of two valence quark distributions at different temperatures T and confinement volumes V. We obtain T_D?T_Fe≈3 MeV and $\text{V}{}_{\mathrm{<mtext>Fe</mtext>}}\text{V}{}_{\mathrm{<mtext>D</mtext>}}\text{≈ 1.3}$.     

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.     

Final state gluon effects in charmed meson decays

In the valence-quark c-decay scheme the decay $\text{D}{}^0\text{→}\text{K}{}^0\text{π}{}^0$ is expected to be strongly suppressed. We suggest that final state soft gluon exchange may account for the rather large branching ratio recently measured for this process, and study two-body decays of charmed mesons in our new scheme.     

Decays of charmed mesons via color-octet decays of the c-quark

We unify the color-octet weak transitions first studied in cq? annihilation models with the coherence structure of c-quark decay models. We find then, with a dominant c-quark decay contribution, $\text{2.3,?}{}_{\mathrm{\tau }}\text{(}\text{D}{}^{\mathrm{+}}\text{)}\text{τ(}\text{D}{}^0\text{)?3.0}$ and τ(D⁺)≈7.5×10^?13 s, not inconsistent with the trends in the experimental results.     

Charge properties of the hadronic system in vp and νp interactions

Charge properties of the hadronic systems from νp and $\text{ν}\text{p}$ scattering in BEBC are studied in the framework of the quark-parto model (QPM). The average charges $\text{〈Q}{}_{\mathrm{<mtext>jet</mtext>}}\text{〈}{}^{\mathrm{<mtext>\nu </mtext>}}$ and $\text{〈Q}{}_{\mathrm{<mtext>jet</mtext>}}\text{〈}{}^{\mathrm{<mtext>\nu </mtext>}}$ of a quark jet and a d-qua jet, respectively, are determined according to two different methods. The difference $\text{〈Q}{}_{\mathrm{<mtext>jet</mtext>}}\text{〈}{}^{\mathrm{\nu }}\text{? 〈Q}{}_{\mathrm{<mtext>jet</mtext>}}\text{〈}{}^{\mathrm{<mtext>\nu </mtext>}}$ is in agreement with e QPM value of 1. Scaling of charge and energy flow in the angular variable λ is demonstrated. The ratios $\text{ΔQ}{}^{\mathrm{<mtext>\nu </mtext>}}\text{/ΔQ}{}^{\mathrm{\nu }}$ of charge flows in νp a $\text{ν}\text{p}$ scattering are in accord with the QPM in both hemispheres.     

Analysis of π N → K Λ and KN → π Λ using fixed-t dispersion relations,fesr and duality

A simultaneous analysis of low-energy (W ? 2 GeV) data for the reactions π^?p→ K^OΛ and K^?p → π^OΛ has been made using the hypothesis of two-component duality combined with fixed-t dispersion relations. Results are presented for the $\text{?}{}^1\text{Λπ}$ and $\text{N}{}^1\text{Λ}\text{K}$ couplings. The low-energy amplitudes are used to evaluate FESR integrals and lead to large EXD breaking for the $\text{K}{}_{\mathrm{<mtext>V</mtext>}}{}^1\text{?}\text{K}{}_{\mathrm{<mtext>T</mtext>}}{}^1$ helicity flip amplitudes.