Showing papers on "Meson published in 1983"
TL;DR: In this paper, the authors measured the deepinelastic electron scattering from carbon up to and including the Δ-region at 36°, 60°, 90° and 145°.
265 citations
TL;DR: In this article, the authors calculate the spectrum of the four ground state hybrid ( q qg ) nonets, JPC = (0, 1, 2)−+, 1−−, using the MIT bag model to first order in cavity perturbation theory.
224 citations
CERN1
TL;DR: In this article, the authors measured the contribution of charm to the nucleon structure function and derived the cross sections for real photoproduction (Q 2 = 0) of charm in the current fragmentation region.
163 citations
TL;DR: In this article, the spectrum of the ground state nonets, JPC = (0, 1, 2)−+; 1−− is calculated in the MIT bag model including O(αs) energy shifts.
159 citations
TL;DR: In this article, an effective Lagrangian for composite σ, π, ω and ρ mesons is derived from a four-quark theory of the Nambu-Jona-Lasinio type.
Abstract: An effective Lagrangian for composite σ, π, ω and ρ mesons is derived from a four-quark theory of the Nambu-Jona-Lasinio type. We study the various mutual relations between the renormalized parameters of this model. If electro-weak interactions are added, the model provides a dynamical foundation of vector-meson dominance.
153 citations
TL;DR: In this paper, a general method is proposed for the QCD based calculations of form factors at intermediate Q 2 and of the partial widths of the low-lying mesonic resonances.
145 citations
TL;DR: In this paper, a potential model for hadrons based on the strong coupling flux tube limit of QCD was constructed, with quark and string-like degrees of freedom, which offers a simple and unified framework in which not only ordinary mesons and baryons but also multiquark states, hermaphrodites and pure glue states can be discussed.
143 citations
TL;DR: In this article, flux-tube dynamics and asymptotic freedom are incorporated into a semirelativistic quark model of baryons and mesons and good agreement with the energy levels of spin-averaged multiplets of mesons was obtained using conventional values for the strong-interaction coupling constant, string tension, and constituent quark mass.
Abstract: SU(3) flux-tube dynamics and asymptotic freedom are incorporated into a semirelativistic quark model of baryons and mesons. Good agreement with the energy levels of spin-averaged multiplets of mesons and baryons is obtained using conventional values for the strong-interaction coupling constant ${\ensuremath{\alpha}}_{s}$, the string tension $\sqrt{\ensuremath{\sigma}}$, and the constituent quark mass $m$. We calculate meson energy levels with angular momentum $L=0, 1, 2, 3, \mathrm{and} 4$ and baryon levels with $L=0, 1, \mathrm{and} 2$ to within 3% of their experimental values. Baryon radial excitations are also considered and the Roper resonance is calculated with \ensuremath{\sim}5% error. The three-body wave equation for the baryons is solved approximately using variational Monte Carlo methods which have been developed previously for nuclear-physics problems.
133 citations
TL;DR: In this paper, the Compton effect on pion in the reaction π − A → A π− γ st 40 GeV/c was detected and for the first time the charged pion polarizability was obtained α π = (6.8 ± 1.4) × 10 −43 cm 3.
129 citations
CERN1
TL;DR: In this paper, the authors discussed the QCD sum rules for the correlators of pseudoscalar currents with quantum numbers of π, K, η, Ϸ′ mesons, and concluded that all these phenomena are very well reproduced by this model.
119 citations
TL;DR: In this paper, the relation between lattice and local operators used in Monte Carlo simulations to evaluate the meson decay constants was computed, at first order in perturbation theory.
CERN1
TL;DR: In this article, a simple structure of the charged fermion mass matrix was suggested, motivated in part by grand unified theories, and relations obtained predict a very small b → u matrix element, a B meson life time τB ≳ 5 × 10−13s, and a range of values for the top quark mass.
TL;DR: In this article, the authors used radiative transitions involving neutral mesons with J/sup P/ = 0/sup -/ (eta,eta,iota(1440)) and 2/sup +/ (f,f,theta(1640)) to provide information on the light-quark content of these mesons, and to test predictions of models in which these states are quarkonium-gluonium mixtures.
Abstract: Radiative transitions involving neutral mesons with J/sup P/ = 0/sup -/ (eta,eta',iota(1440)) and 2/sup +/ (f,f',theta(1640)) are used to provide information on the light-quark content of these mesons, and to test predictions of models in which these states are quarkonium-gluonium mixtures. Some suggested observations include (l) phi..-->..eta'..gamma.., predicted to have a branching ratio of 7 x 10/sup -5/ in the standard quarkonium picture of eta', (2) f'..--> gamma gamma.., predicted to have a partial width > or approx. =200 eV if f' = ss-bar but very sensitive to possible destructive interference from small nonstrange-quark admixtures, and (3) iota(1440)..--> gamma gamma.. and theta(1640)..--> gamma gamma.., which will be easily detectable unless these states are almost totally free of quarkonium admixtures.
TL;DR: In this article, a potential model for mesons is presented, which combines quark confinement and strong decay in a realistic approach, and the multichannel Schr\"odinger formalism is employed to describe a system of one or more permanently closed quark-antiquark channels in interaction with several two-meson channels.
Abstract: A potential model for mesons is presented, which combines quark confinement and strong decay in a realistic approach. The multichannel Schr\"odinger formalism is employed to describe a system of one or more permanently closed quark-antiquark channels in interaction with several two-meson channels. For the potential in the $q\overline{q}$ channels a harmonic oscillator with constant frequency is taken. As for the meson channels only Okubo-Zweig-Iizuka-rule-allowed decays into two mesons of the pseudoscalar or vector type are considered. Final-state interactions between these mesons are not yet taken into account. The communication between confined and free channels is supposed to take place via the $^{3}P_{0}$ mechanism, for which a locally approximated transition potential is derived. In order to obtain an analytic solution for the $S$ matrix, the transition potential is treated by using a multi-$\ensuremath{\delta}$-shell method. Kinematically relativistic corrections and color splitting allow a fairly successful treatment of pseudoscalar as well as vector mesons for all quark flavors. The results are confronted with the data and discussed.
TL;DR: In this paper, the potential function for all possible excitations of a gluonic string with fixed ends was extracted from lattice Monte Carlo calculations using a variational technique and the spectrum of mesonic states, including those with exotic J PC, was presented.
TL;DR: In this paper, it is shown that at high momentum transfer, the running coupling constant α S (q 2) assumes small values and perturbation theory can be applied, but at low energies, the perturbative approach does not work.
TL;DR: In this article, the production of single mesons and opposite side pairs of mesons in hadron-nucleus and nucleus nucleus collisions is calculated in the framework of the QCD parton model, with the assumption that quarks and gluons undergo multiple scattering in the nucleus.
Abstract: Production of single mesons and opposite side pairs of mesons in hadron-nucleus and nucleusnucleus collisions are calculated in the framework of the QCD parton model, with the assumption that quarks and gluons undergo multiple scattering in the nucleus. A comparison with all available data is made. It is also shown that the anomalous nuclear enhancement, especially its dependence on the flavour, can be quantitatively described within the model. Furthermore, we predict no enhancement for symmetric pairs as it seems to be indicated by the data. Predictions for largep
T production in α−α scattering at ISR are made.
TL;DR: In this article, a simple analytic unitary model was proposed to obtain a parametrization of low energy photon production of ππ and K\(\bar K\) pairs in terms of a few parameters related to the γγ width of the scalar and tensor resonances.
Abstract: We describe a simple analytic unitary model which provides with a parametrization of low energy (from threshold up to 1.4GeV) two photon production of ππ andK\(\bar K\) pairs in term of a few parameters related to the γγ width of the scalar and tensor resonances. It can be useful for analysing data because of the large continuum found in γγπ+π− production besides thef0 (1,270) peak in recent experiments. We show that the present data already provides a strong evidence for the existence of a broad low mass scalar state, the old σ or e (600) with a γγ width of 5 to 9KeV, and that it will be difficult to get more information on the controversialS* parameters from ππ pair production only. In thef0 range we explain the downwards shift of the π+π− peak but we expect the π0π0 peak around 1.27–1.29 GeV which could raise the question either of systematic errors in mass calibration of crystal Ball experiment or of the precise value of thef0 mass.
TL;DR: In this paper, the production of π± and K± mesons and of protons and antiprotons ine+e− annihilation has been measured at c.m. energies of W=14, 22 and 34GeV.
Abstract: The inclusive production of π± andK± mesons and of protons and antiprotons ine+e− annihilation has been measured at c.m. energies ofW=14, 22 and 34GeV. Using time of flight measurements and Cerenkov counters the full momentum range has been covered. Differential cross sections and total particle yields are given. At particle momenta of 0.4 GeV/c more than 90% of the charged hadrons are pions. With increasing momentum the fraction of pions among the charged hadrons decreases. AtW=34 GeV and a momentum of 5 GeV/c the particle fractions are approximately π±:K±:p,\(\bar p = 0.55:0.3:0.15\). On average an event atW=34 GeV contains 10.3±0.4π±, 2.0±0.2K± and 0.8±0.1p,\(\bar p\). In addition, we present results on baryon correlations using a sample of events where two or more protons and/or antiprotons are observed in the final state.
TL;DR: In this article, the influence of pionic corrections on multi-quark hadrons was investigated and the implications of these corrections on six quark configurations were discussed. And the bag parameters from ordinary baryons and mesons were determined.
Abstract: The authors investigate the influence of pionic corrections on multi-quark hadrons. After determining the bag parameters from ordinary baryons and mesons, they discuss the implications for six-quark configurations.
01 Dec 1983
TL;DR: By means of relativistic QCD sum rules, the leptonic decay constants of the pseudoscalar D and B mesons were calculated as discussed by the authors, f/sub D/approx.
Abstract: By means of relativistic QCD sum rules the leptonic decay constants of the pseudoscalar D and B mesons are calculated: f/sub D/approx. =170 MeV and f/sub B/approx. =130 MeV.
TL;DR: In this paper, the authors present a consistent and unified study of the spectrum of low-lying mesons, baryons, and glueballs using the MIT bag model, incorporating several improvements in the model.
Abstract: We present a consistent and unified study of the spectrum of low-lying mesons, baryons, and glueballs using the MIT bag model, incorporating several improvements in the model. We correct for the center-of-mass motion, use a running coupling ${\ensuremath{\alpha}}_{s}(R)$, include self-energy terms for quarks and gluons confined in a cavity, and get the bag constant from a model of the QCD vacuum. Our fit to the meson and baryon spectrum, including the pion, is good and predictions for the glueball spectrum are given.
TL;DR: In this article, a method is developed which allows the determination of a local G-operator, i.e. G without the bare interaction V, in terms of meson-exchange-type interactions.
TL;DR: In this article, the light quark masses were calculated on the basis of finite energy sum rules and the obtained result [(mu+md(GeV)∼20MeV] allows us to estimate the ratio mb/ms∼ 20 which should be compared with the prediction of the SU(5) model, mb /mπ/ms≈ 17.
TL;DR: In this paper, a simple method was presented to compute the Wilson expansion coefficients for T-products in QCD with light quarks, using this method in the framework of QCD sum rules they predicted the masses of quark-antiquark-gluon states with JPC = 1−+, 0++, 1+− and 0−−.
TL;DR: The D∗± energy spectrum is hard, with a maximum near χ = 0.6. as discussed by the authors showed that a large fraction of charm quark production yields D ∗ mesons, which is consistent with that expected in the standard theory for weak neutral currents.
TL;DR: In this article, a general expression for the two-photon form factor of neutral pseudoscalar mesons is given in a quark triangle model, which is in agreement with other calculations based on vector meson dominance, giving a new example of Q2 duality.
TL;DR: In this article, color-magnetic interactions (one-gluon exchange) are incorporated into a semirelativistic quark model and the spectra of ground states and orbital and radial excitations of light mesons, light baryons, charmonium, and $b$-quarkonium are calculated by treating the magnetic splitting exactly by variational methods.
Abstract: Color-magnetic interactions (one-gluon exchange) are incorporated into a semirelativistic quark model and the spectra of ground states and orbital and radial excitations of light mesons, light baryons, charmonium, and $b$-quarkonium are calculated by treating the magnetic splitting exactly by variational methods. The $\ensuremath{\pi}\ensuremath{-}\ensuremath{\rho}$ splitting is fit and the $N\ensuremath{-}\ensuremath{\Delta}$ splitting is predicted in excellent agreement with experiment. In general, spin-spin and tensor splittings among light mesons and light baryons are calculated in good agreement with experiment. The splittings in heavy-meson spectroscopy are also predicted accurately, including the $P$-wave states of charmonium and $b$-quarkonium. Some problems and limitations of the quark-model description of the light mesons and baryons are emphasized. Spin-orbit splittings in the light mesons and $P$-wave baryon multiplets are calculated, but a unified understanding of the systematics is not obtained. Radial excitations in the meson and baryon systems are generally in error by 100-150 MeV, and the systematics are not understood.
TL;DR: In this paper, a multi-chain fragmentation model for particle production in hadron-hardon and hadronnucleus collisions for all kinds of incident hadrons is investigated, and the model is implemented using a realistic Monte Carlo model for the fragmentation of quarkantiquark, quark-diquark and diquark-antidiquark chains into mesons, baryons, and their resonances.
Abstract: We investigate a multi-chain fragmentation model for particle production in hadron-hardon and hadron-nucleus collisions for all kinds of incident hadrons. The model is implemented using a realistic Monte Carlo model for the fragmentation of quarkantiquark, quark-diquark, and diquark-antidiquark chains into mesons, baryons, and their resonances. We assume that these jets have universal properties which are the same in electron-positron, lepton-hadron, and hadron-hadron collisions. Energy-momentum and all additive quantum numbers are exactly conserved. The model is compared with exclusive as well as inclusive particle-production cross-sections. It is well suited to the study of complete exclusive events and the flavour composition of secondary multiparticle systems.