Showing papers on "Meson published in 1978"
TL;DR: In this article, a comprehensive treatment of the charmonium model of the ψ family is presented, where the model's basic assumption is a flavor-symmetric instantaneous effective interaction between quark color densities.
Abstract: A comprehensive treatment of the charmonium model of the ψ family is presented. The model's basic assumption is a flavor-symmetric instantaneous effective interaction between quark color densities. This interaction describes both quark-antiquark binding and pair creation, and thereby provides a unified approach for energies below and above the threshold for charmed-meson production. If coupling to decay channels is ignored, one obtains the “naive” model wherein the dynamics is completely described by a single charmed-quark pair. A detailed description of this “naive” model is presented for the case where the instantaneous potential is a superposition of a linear and Coulombic term. A far more realistic picture is attained by incorporating those terms in the interaction that couple charmed quarks to light quarks. The coupled-channel formalism needed for this purpose is fully described. Formulas are given for the inclusive e + e − cross section and for e + e − e annihilation into specific charmed-meson pairs. The influence of closed decay channels on ψ states below charm threshold is investigated, with particular attention to leptonic and radiative widths.
995 citations
TL;DR: In this article, a model of the properties of the jet of mesons generated by a fast outgoing quark is presented, where the meson that contains the original quark leaves momentum and flavor to a remaining jet in which the particles are distributed like those of the original jet.
759 citations
TL;DR: An explicit form for the charmed quark fragmentation function DCc(z) into hadrons has been obtained with the help of the "reciprocity relation" and the c-quark distribution function in charmed mesons as mentioned in this paper.
203 citations
TL;DR: In this paper, the authors show that only a combined version of light quark qq→cc fusion and gluon gg→CC fusion mechanisms can account for the various total cross section beam ratios as well as for the observed xF distribution.
Abstract: Using the recent CERN and Fermilab measurements for J/ψ production by π±, K±, p and p beams we show, within the framework of QCD, that only a combined version of light quark qq→cc fusion and gluon gg→cc fusion mechanisms can account for the various total cross section beam ratios as well as for the observed xF‐distributions.
159 citations
TL;DR: In this paper, a model of mesons composed of a quark, an antiquark, and a gluon is proposed, where the binding of the constituents is provided by a confining linear potential between the gluons and the quarks.
Abstract: A model of mesons composed of a quark, an antiquark, and a gluon is proposed. The binding of the constituents is provided by a confining linear potential between the gluon and the quarks. The lowest states of the model are described, and their relative masses evaluated, for the case of heavy (charmed) quarks, i.e., ccg states.
144 citations
TL;DR: In this article, the authors used the lowest order in the perturbation series for quantum chromodynamics to obtain an estimate for the contribution of hard-scattering processes involving vector gluons to the production of hadrons at large transverse momentum.
Abstract: We use a calculation based on the lowest order in the perturbation series for quantum chromodynamics to obtain an estimate for the contribution of hard-scattering processes involving vector gluons to the production of hadrons at large transverse momentum. Some simple models for the distribution of gluons in a proton and for the distribution of hadrons within a hard gluon jet are presented and used to calculate the process $\mathrm{pp}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}X$. At $\sqrt{s}=53$ GeV we find that the contribution of the subprocess $\mathrm{qV}\ensuremath{\rightarrow}\mathrm{qV}$ is comparable to that of $\mathrm{qq}\ensuremath{\rightarrow}\mathrm{qq}$. The resulting cross sections are rather close to the CERN ISR data in magnitude. It is possible that small corrections arising, for example, from higher-order terms in the perturbation expansion might lead to a detailed fit to these data. At higher energies, such as those to be obtained in proposed new experimental facilities, our results indicate that the mechanisms $\mathrm{VV}\ensuremath{\rightarrow}\mathrm{VV}$ and $\mathrm{qV}\ensuremath{\rightarrow}\mathrm{qV}$ may dominate over $\mathrm{qq}\ensuremath{\rightarrow}\mathrm{qq}$ in much of the accessible kinematic regime. We briefly consider some experimental consequences of possible gluon dominance.
123 citations
TL;DR: In this paper, the rates of two-body weak decays of charmed mesons, on the basis of a simple quark recombination scheme, were derived directly in terms of the relative strength of the 20 and 84 SU(4) components of the effective weak lagrangian.
121 citations
TL;DR: In this paper, the pion form factor is measured in the reaction e+e− → π+π− for center of mass energies in the range 480-1100 MeV.
114 citations
TL;DR: In this article, a generalized analysis of nuclear β decay and semileptonic hyperon and K/sub e/3 decays was carried out and the results were used to determine two quark mixing angles in the sequential Weinberg-Salam model.
Abstract: We carry out a new, generalized analysis of nuclear ..beta.. decay and semileptonic hyperon and K/sub e/3 decays. The results are used to determine two quark mixing angles in the sequential Weinberg-Salam model.
112 citations
TL;DR: In this article, the branching ratio for stopping K− meson interactions at rest in hydrogen was investigated. But the branching ratios were not shown to be consistent with the previous results, namely 2.38±0.04 and 2.35±0.07.
112 citations
TL;DR: In this article, two-quark-two-antiquark mesons which couple strongly to baryon-antibaryon channels are classified and the quantum numbers and masses of prominent states are predicted from the MIT bag model.
Abstract: Two-quark-two-antiquark mesons which couple strongly to baryon-antibaryon channels are classified. The quantum numbers and masses of prominent states are predicted from the MIT bag model. The couplings of ${Q}^{2}{\overline{Q}}^{2}$ states to $B\overline{B}$ are estimated using the $^{3}P_{0}$ model and peripherality. Though most ${Q}^{2}{\overline{Q}}^{2}$ states do not couple strongly to $B\overline{B}$, many prominent resonances remain. Important ${Q}^{2}{\overline{Q}}^{2}$ resonances in the following processes are enumerated and discussed: elastic $N\overline{N}$ scattering, $N\overline{N}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, $N\overline{N}$ resonances at or below threshold, and exotic isotensor baryon-antibaryon resonances.
TL;DR: In this paper, the mass of the η c meson is calculated by means of QCD sum rules, and the spectrum of the 0 − states of charmonium contains a single prominent resonance, like the J/ψ in the case of vector states, not 2.83.
TL;DR: In this paper, the deuteron photodisintegration amplitude in terms of the leading diagrams has been extended to include the meson exchange currents, and the model reproduces the available experimental data from threshold up to E γ = 800 MeV.
TL;DR: In this paper, a model is presented which is capable of calculating simultaneously the spectra of pions, nucleons, and light nuclei from the collision of relativistic heavy ions based on the nuclear thermodynamics of Mekjian and Kapusta.
Abstract: A model is presented which is capable of calculating simultaneously the spectra of pions, nucleons, and light nuclei from the collision of relativistic heavy ions It is based on the nuclear thermodynamics of Mekjian and Kapusta Maximum use is made of the conservation laws for baryon number, charge, energy, momentum, and angular momentum Single particle inclusive cross sections were calculated and compared with experiment for a wide range of beam energies and observed fragments Except for some conflicting normalizations and high-energy pions good agreement is found The density at which hadrons effectively cease to interact, which is the only parameter in the model, is determined to be 012 hadrons/${\mathrm{fm}}^{3}$NUCLEAR REACTIONS Relativistic heavy ions; firestreaks, hadronic thermal equilibrium; calculated differential cross sections of ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$, $p$, $d$, $t$, $^{3}\mathrm{He}$, $^{4}\mathrm{He}$; comparisons with experiment
TL;DR: In this paper, an approach to reproduce the experimental Coulomb capture ratios of negative mesons in chemical compounds is proposed, assuming that the decisive role in the capture process is played by not too strongly bound electrons.
TL;DR: In this article, the multiplicities of secondary hadrons in the fragmentation region of a projectile are computed as a function of the atomic number of the target, A. The calculation is based on the notion of a nucleon (meson) composed of three (two) spatially discrete constituent quarks.
TL;DR: In this article, the authors estimate the cross section for charmed particle production in proton-proton scattering and show that the dominant mechanism at high energy involves the annihilation of constituent gluon partons.
TL;DR: In this article, it was shown that if in a calculation of high transverse-momentum mesons production in hadron-hadron collisions one includes not only the scale-breaking effects that might be expected from asymptotically free theories but also the effects due to the transverse momentum of quarks in hadrons, then the results are not inconsistent with the single-particle cross-section data.
Abstract: It is shown that if in a calculation of high--transverse-momentum mesons production in hadron-hadron collisions one includes not only the scale-breaking effects that might be expected from asymptotically free theories but also the effects due to the transverse momentum of quarks in hadrons,then the results are not inconsistent with the single-particle cross-section data.
TL;DR: In this paper, a pair of covariant wave equations describing mesons as confined q q pairs and realizing a spontaneously broken chiral symmetry were proposed, and the system is Hamiltonian and does not contain unphysical solutions.
TL;DR: In this article, a simple phenomenological non-relativistic colored quark model was proposed to relate meson and baryon masses, and the model predicts a rich closely spaced spectrum for the four quark system.
TL;DR: In this article, the authors systematically studied the production of resonances in K + p interactions at 32 GeV/c and gave total production cross sections for three baryon resonances, five vector and three 2 + tensor mesons.
TL;DR: In this article, the process e + e − → HX where H is a meson consisting of a heavy quark Q and a light antiquark q, is considered and it is suggested that in QCD the production of H-meson with z = 2E H / s not close to 1 must be accompanied by the gluonic jet emission.
TL;DR: In this paper, the meson distributions from quark fragmentation with particular emphasis on the importance of a vector meson production of the size observed at present are treated, with the sole constraints coming from energy and momentum conservation.
CERN1
TL;DR: In this article, the authors measured the invariant cross sections for the production of π ± and K ± mesons in proton-proton collisions in the range 0.41 x p T x = 2 p L/√ s and p L, p T are the longitudinal and transverse components of the momentum of the meson.
TL;DR: In this article, the nonrelativistic Schrodinger equation is used with confinement potentials that are either fractional power laws or logarithmic functions of the radial coordinate to investigate the spectrum of states, leptonic decay widths, and radiative decays of the ψ family of resonances.
TL;DR: In this paper, the amplitude of the regeneration by electrons was determined by comparing the rates of coherent (transmission) regeneration and of diffraction regeneration at a double beam, and the authors made a determination from 30 to 100 GeV/c using a novel approach.
Abstract: The amplitude of ${K}_{S}$ regeneration by electrons, $\frac{{{f}_{21}}^{e}}{k}=\ensuremath{-}(\frac{\ensuremath{\alpha}}{3})〈{R}^{2}〉$ ($〈{R}^{2}〉$ is the ${K}^{0}$ charge radius), can be determined by comparing the rates of coherent (transmission) regeneration and of diffraction regeneration at ${q}^{2}=0$. We made a determination from 30 to 100 GeV/c, using a novel approach: Two distinct Pb regenerators, of optimized thicknesses, were exposed to a double beam, and interchanged every burst. We find $〈{R}^{2}〉=\ensuremath{-}(0.054\ifmmode\pm\else\textpm\fi{}0.026)$ ${\mathrm{fm}}^{2}$. The sign, magnitude, and $p$ independence agree with predictions.
TL;DR: In this article, the contributions to the electron scattering cross section arising from two-nucleon emission via meson exchange current interactions are calculated in the Fermi gas model and sizeable effects are found at large energy transfers and lead to a partial filling of the "dip" between the quasielastic peak and the analogous peak associated with the 3-3 resonance.
01 Jan 1978
TL;DR: In this article, the Hadronic Feynman graphs are developed which strongly resemble dual diagrams and the new field quanta consist of all quark antiquark bound states in the ladder approximation.
Abstract: Local quark gluon theories are converted into bilocal field theories via functional techniques. The new field quanta consist of all quark antiquark bound states in the ladder approximation. They are called “bare hadrons”. Hadronic Feynman graphs are developed which strongly resemble dual diagrams. QED is a special case with the “bare hadrons” being positronium atoms. Photons couple to hadrons via intermediate vector mesons in a current-field identity. The new theory accommodates naturally bilocal currents measured in deep-inelastic e p scattering Also these couple via intermediate mesons.
TL;DR: In this paper, the properties of the final-state hadronic system in antineutrino-proton charged-current interactions are presented, and the average energy of the events is - 30 GeV, but there are some interactions beyond 100 GeV.
Abstract: The properties of the final-state hadronic system in antineutrino-proton charged-current interactions are presented. The events were observed in Fermilab 15-foot hydrogen bubble chamber. The average energy of the events is - 30 GeV, but there are some interactions beyond 100 GeV. The mean multiplicity of the charged hadrons varies as = (0.06 +- 0.60) + (1.22 +- 0.03)lnW/sup 2/ for hadronic masses W in the range 1.0 < W/sup 2/ < 50 GeV/sup 2/. By contrast, the multiplicity depends only weakly on the four-momentum transfer between the leptons. The mean pion multiplicities for events with three or more charged tracks are found to be = 1.64 +- 0.04, = 1.16 +- 0.13, for ..pi../sup -/ and ..pi../sup 0/ production, respectively. By comparing the number of positive tracks with ..pi../sup -/ data from neutrino production, we deduce a mean proton multiplicity of 0.53 +- 0.15. The single-particle distributions in both longitudinal and transverse momentum are found to be similar to those for nondiffractive production in hadronic collisions. The fragmentation properties of the final-state d quarks are compared to the expectations of the quark-parton model. The fraction of observed neutral-strange-particle production for events with three or more charged tracks is 0.08 +-more » 0.015 and is consistent with coming completely from associated production.« less
TL;DR: NegNegative-pion production in relativistic heavy-ion collisions has been studied in a triggered streamer-chamber experiment with projectile nuclei /sup 12/C and /sup 40/Ar in the energy range 0.4-2.1 GeV/nucleon incident on targets LiH, NaF, BaI/sub 2/, and Pb/sub 3/O/sub 4/.
Abstract: Negative-pion production in relativistic heavy-ion collisions has been studied in a triggered streamer-chamber experiment with projectile nuclei /sup 12/C and /sup 40/Ar in the energy range 0.4-2.1 GeV/nucleon incident on targets LiH, NaF, BaI/sub 2/, and Pb/sub 3/O/sub 4/. Negative-pion yields, multiplicity distributions, and angular and momentum distributions are reported.