Showing papers on "Meson published in 1986"
TL;DR: The three quark system is studied in a relativized version of the quark potential model with chromodynamics and the spectrum of baryons is described with parameters consistent with those of an analogous study of meson spectroscopy.
Abstract: We have studied the three quark system in a relativized version of the quark potential model with chromodynamics. With parameters consistent with those of an analogous study of meson spectroscopy we obtain a successful description of the spectrum of baryons. The model naturally explains the apparent absence of spin‐orbit interactions in baryons.
2,203 citations
TL;DR: In this article, a review of the recent progress in extracting the equation of state of hot dense hadronic matter from relativistic heavy ion collisions is presented, and a comparison of the distinct theoretical predictions to recent high multiplicity selected 4π data on fragment formation, pion production and collective sidewards flow is presented.
726 citations
TL;DR: In this article, an effective low-energy lagrangian of composite scalar, pseudoscalar, vector and axial-vector mesons was derived by bosonization of an extended Nambu-Jona-Lasinio type of quark model with explicit breaking of chiral U (n) × U(n) symmetry.
392 citations
TL;DR: In this article, a non-relativistic meson model is proposed for the description of the heavy and light vector and pseudo-scalar mesons, which yields a complete nonet below 1 GeV.
Abstract: A unitarized non-relativistic meson model which is successful for the description of the heavy and light vector and pseudo-scalar mesons yields in its extension to the scalar mesons for the same model parameters a complete nonet below 1 GeV. In the unitarization scheme real and virtual meson meson decay channels are coupled to the quark antiquark confinement channels. The flavor dependent harmonic oscillator confining potential itself has bound states ɛ(1.3 GeV),S(1.5 GeV), δ(1.3 GeV), κ(1.4 GeV), similar to the results of other bound stateq
$$\bar q$$
models. However, the full coupled channel equations show poles at ɛ(0.5 GeV),S(0.99 GeV), δ(0.97 GeV), κ(0.73 GeV). Not only these pole positions can be calculated in our model also cross sections and phase shifts in the meson scattering channels which are in reasonable agreement with the available data for ππ, ηπ andKπ inS-wave scattering.
270 citations
TL;DR: The values of the quark-mass ratios can be constrained by limiting the size of second-order corrections to the squares of meson masses by finding that for specific values of presently unmeasured phenomenological parameters one can have a massless u quark.
Abstract: We investigate the current-mass ratios of the light quarks by fitting the squared meson masses to second order in chiral-symmetry breaking, determining corrections to Weinberg's first-order values: m/sub u//m/sub d/ = 0.56, m/sub s//m/sub d/ = 20.1. We find that to this order, m/sub s//m/sub d/ is a known function of m/sub u//m/sub d/. The values of the quark-mass ratios can be constrained by limiting the size of second-order corrections to the squares of meson masses. We find that for specific values of presently unmeasured phenomenological parameters one can have a massless u quark. In that case 30% of the squares of meson masses arise from operators second order in chiral-symmetry breaking.
241 citations
TL;DR: In this article, the authors examined the system consisting of two quarks and two antiquarks with equal or unequal masses and showed that the virtual meson-meson components of the wave function can be solved by empirical or systematic variational methods.
Abstract: In the framework of simple non-relativistic potential models, we examine the system consisting of two quarks and two antiquarks with equal or unequal masses. We search for possible bound states below the threshold for the spontaneous dissociation into two mesons. We solve the four body problem by empirical or systematic variational methods and we include explicitly the virtual meson-meson components of the wave function. With standard twobody potentials, there is no proliferation of multiquarks. With unequal quark masses, we obtain however exotic\(\left( {\bar Q\bar Qqq} \right)\) bound states with a baryonic antidiquark-quark-quark structure very analogous to the heavy flavoured (Q′qq) baryons.
190 citations
TL;DR: In this article, the large-N limit is used to obtain a consistent picture of the K → ππ matrix elements and it is confirmed that the dominant Q6 penguin matrix elements are enhanced by an order of magnitude compared to those of the current current current operators and this result is consistent with chiral perturbation theory.
156 citations
TL;DR: The constituent-quark model is used to predict the electron spectra in semileptonic meson decays, and particular attention is paid to the end-point region of the spectrum in B decays.
Abstract: We use the constituent-quark model to predict the electron spectra in semileptonic meson decays. Particular attention is paid to the end-point region of the spectrum in B decays, which is important to the determination of the b..-->..u weak mixing angle.
145 citations
TL;DR: In this paper, the authors review the progress that has been made in understanding weak interaction effects in hadrons and their focus is on the quark model and its role in connecting hadronic processes with the underlying SU(2) L × U(1) weak interaction theory.
142 citations
TL;DR: High-statistics data from two exposures of the BNL 7-foot deuterium bubble chamber to a wide-band-neutrino beam with an average energy of 1.6 GeV were analyzed for exclusive pion production in charged-current neutrino-deuterium interactions to present new results for single-pion and multipion production.
Abstract: High-statistics data from two exposures of the BNL 7-foot deuterium bubble chamber to a wide-band-neutrino beam with an average energy of 1.6 GeV were analyzed for exclusive pion production in charged-current neutrino-deuterium interactions. For the single-pion production reactions, the properties of ${\ensuremath{\Delta}}^{++}$ production and decay as well as the final results of an isospin analysis are presented. New results for single-pion and multipion production are also presented.
137 citations
TL;DR: In this paper, the authors investigate the ability of a relativistic mean field theory to reproduce nuclear ground state properties by an exhaustive fit to experimental data and find that the bulk properties of nuclei from 16O to 208Pb can be adjusted very well.
Abstract: We investigate the ability of a relativistic Mean-Field theory to reproduce nuclear ground state properties by an exhaustive fit to experimental data. We find that the bulk properties of nuclei from16O to208Pb can be adjusted very well. There remain problems with level density and fluctuations in the charge density similar as in fits using the conventional Skyrme Hartree-Fock model.
Book•
01 Jan 1986
TL;DR: In this article, the authors present a model of the Dirac nuclear structure in light nuclei using a Finite Range Dirac Interaction and a dynamical basis for NN Amplitudes and Dirac Optical Potentials.
Abstract: RELATIVISTIC DYNAMICS: Nonrelativistic and Relativistic Multiple Scattering The Meson Theory of Nuclear Forces and Nuclear Matter Electronuclear Reactions and Meson Exchange Currents Relativistic Meson-Nucleon Models: Applications to Bound and Scattering States Antiproton Physics at Intermediate Energy Development of the Dirac Scattering Approach Implications of Dirac Nuclear Structure for Electron Scattering A Relativistic Schematic Model of Nuclear Structure in Light Nuclei Studies of Nuclear Structure Using a Finite Range Dirac Interaction Relativistic and Nonrelativistic Dynamics in the (e,e'p) Reaction A Dynamical Basis for NN Amplitudes and Dirac Optical Potentials Relativistic vs Nonrelativistic Models of Proton-Nucleus Inelastic Scattering Recent Experimental Results in (e,e'p) Antiprotons Are Another Matter QUARK-NUCLEAR PHYSICS: Deep Inelastic Scattering with Application to Nuclear Targets Nuclear Physics from the Quark Model with Chromodynamics Hadronic Matter on a Lattice Low Energy Phenomenology with Skyrmions Nuclear Force in a Quark Model Two Baryon Systems in the Nonrelativistic Quark Model Covariant Condensate Wave Functions in the Skyrme Model Nuclei in the Skyrme Model.
Journal Article•
TL;DR: In this paper, the secondary spectra of neutral pi-mesons produced in proton-proton collisions, at energies between threshold and a few GeV, are compared on the basis of accelerator data and found to show the isobaric model to be superior.
Abstract: Isobaric and scaling model predictions of the secondary spectra of neutral pi-mesons produced in proton-proton collisions, at energies between threshold and a few GeV, are compared on the basis of accelerator data and found to show the isobaric model to be superior. This model is accordingly used, in conjuction with a scaling model representation at high energies, in a recalculation of the pi exp (0) gamma-radiation's contribution to the diffuse galactic gamma background; the cosmic ray-induced production of photons (whose energy exceeds 100 MeV) by such radiation occurs at a rate of 1.53 x 10 to the -25 photons/(s-H atom). These results are compared with previous calculations of this process as well as with COS-B observations of the diffuse galactic gamma-radiation.
TL;DR: In this paper, a variational approach is developed which successfully predicts meson masses with baryon masses as input and gives nearly model-independent estimates of four-quark masses by using trial wave functions whose interaction energies are approximately given by known hadron masses.
TL;DR: In this article, a combined semiphenomenological analysis of the low-energy p p annihilation into two mesons and the p p scattering processes which enter into the description of the initial state before two-meson annihilation is presented.
TL;DR: Two-body decays of charm mesons are analyzed in the quark-diagram formulation, including effects of SU(3) breaking and final-state interactions.
Abstract: Two-body decays of charm mesons are analyzed in the quark-diagram formulation, including effects of SU(3) breaking and final-state interactions. Interesting future experiments are also pointed out.
TL;DR: In this paper, a vector meson dominance model was proposed to predict the quark-gluon substructure of the nucleon at distances ≲ 1 2 fm.
TL;DR: The nonlinear sigma model with the Wess-Zumino term is extended to the low-lying vector meson resonances and the bulk properties of hedgehog skyrmions are investigated.
Abstract: The nonlinear sigma model with the Wess-Zumino term is extended to the low-lying vector meson resonances ..omega.., rho and A/sub 1/. These resonances are treated as chiral gauge multiplets in a minimally broken SU(2)/sub L/xSU(2)/sub R/xU(1)/sub V/ gauge model. The bulk properties of hedgehog skyrmions are investigated. The results indicate a clear improvement over the conventional Skyrme model.
TL;DR: In this paper, the authors prove the existence of minima and study their properties in Skyrme's variational problem, which describes the structure of mesons in a field of weak energy.
Abstract: The solutions of Skyrme's variational problem describe the structure of mesons in a field of weak energy. The problem consists in minimizing the corresponding energy among the functions from ℝ3 toS3 which have a fixed “degree” without making any symmetry assumptions. We prove the existence of minima and study their properties.
TL;DR: This paper extended the Skyrme model to incorporate the vector mesons in a way consistent with the non-Abelian anomalies of QCD and vector-meson dominance, treating them as composite gauge bosons of a hidden SU symmetry.
Abstract: We extend the Skyrme model to incorporate the vector mesons $\ensuremath{\rho}$ and $\ensuremath{\omega}$ in a way consistent with the non-Abelian anomalies of QCD and vector-meson dominance. The vector mesons are treated as composite gauge bosons of a hidden ${\mathrm{SU}(2)}_{V}\ensuremath{\bigotimes}\mathrm{U}(1)$ symmetry. We investigate the bulk properties of hedgehog-type Skyrme solitons in the baryon number $B=1$ sector of this model.
TL;DR: In this article, the scalar G(1590) meson which decays into ηη has been obtained in an experiment at the CERN SPS, where η pairs are detected with the electromagnetic calorimeter GAMS both through their decay into 4γ and into 8γ.
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TL;DR: In this paper, it was shown that the mass of the A1(a1)1++ meson is ≳ 1200 MeV/c2, which is consistent with the properties inferred from hadronic experiments.
TL;DR: In this article, an efficient method for calculating hadronic three-point functions in lattice gauge theory is described. But this method is not suitable for the case of the ρ and K ∗ mesons and the Δ, Σ ∗, and Ξ ∗ baryons.
TL;DR: A simple semiclassical method for calculating physical observables in states with good angular momentum and isospin for models whose mean-field solutions are hedgehogs for theories which have both quark and meson degrees of freedom.
Abstract: A simple semiclassical method is presented for calculating physical observables in states with good angular momentum and isospin for models whose mean-field solutions are hedgehogs. The method is applicable for theories which have both quark and meson degrees of freedom. The basic approach is to find slowly rotating solutions to the time-dependent mean-field equations. A nontrivial set of differential equations must be solved to find the quark configuration for these rotating hedgehogs. The parameters which specify the rotating solutions are treated as the collective degrees of freedom. They are requantized by imposing a set of commutation relations which ensures the correct algebra for the SU(2) x SU(2) group of angular momentum and isospin. Collective wave functions can then be found and with these wave functions all matrix elements can be calculated. The method is applied to a simple version of the chiral quark-meson model. A number of physical quantities such as magnetic moments, charge distributions, g/sub A/, g/sub ..pi..//sub N//sub N/, N-..delta.. mass splitting, properties of the N-..delta.. transition, etc., are calculated.
TL;DR: In this paper, a coupled channel analysis was carried out using a new amplitude analysis of the K0sK0s system produced in the reaction π−p→K 0sK 0sn at 22 GeV/c, which contained about 40 000 new events in the low-t region (|t−tmin|).
TL;DR: In this article, the cross section for the radiative photoproduction of π+ mesons on hydrogen in dependence on the momentum transfer squared has been measured at the 1·2 GeV electron synchrotron PACHRA.
Abstract: The cross section for the radiative photoproduction ofπ+ mesons on hydrogenγp →γπ+n in dependence on the momentum transfer squared has been measured at the 1·2 GeV electron synchrotron PACHRA. Using extrapolation of the data to pion pole the differential cross section for the pion Compton scatteringγπ+ →γπ+ has been obtained, and the electric polarizability of theπ+ meson has been estimated to be\(\alpha _{\pi ^ + }\) =(20±12) x 10-43cm3.
TL;DR: In this article, the authors analyse the QCD sum rules for the exotic quark-antiquark-gluon states called glukonium or hermaphrodite mesons.
Abstract: We analyse the QCD sum rules for the exotic quark-antiquark-gluon states called “glukonium” or “hermaphrodite” mesons. We predict a non-strange resonance of this type at ∼1.5 GeV, a strange one at ∼1.6 GeV and a strange-antistrange one at ∼1.75 GeV. It should be noted that the above values of masses depend crucially on the vacuum expectation value of the gluon field operator .
CERN1
TL;DR: In this article, it was shown that the large angular momentum behavior of the leading Regge trajectory of a meson (q\(\bar q\)) or a baryon (qqq) can be obtained by minimizing the classical energy of the system for given angular momentum.
Abstract: We prove that the large angular momentum behaviour of the leading Regge trajectory of a meson (q\(\bar q\)) or a baryon (qqq) can be obtained by minimizing the classical energy of the system for given angular momentum. A two-body quark-antiquark linear potential plus relativistic kinematics produces asymptotically linear Regge trajectories for mesons. For baryons we take either a sum of two-body potentials with half strength or a string of minimum length connecting the quarks, and find in both cases that the favoured configuration is a quark-diquark system and that the baryon and meson trajectories have the same slope. Short-distance singularities of the potential are shown to be unimportant.
TL;DR: The effects of spin-dependent charge-symmetry-breaking forces can be measured in elastic scattering and it is found that a term in the one-pion exchange potential arising from the neutron-proton mass difference is dominant.
Abstract: The effects of spin-dependent charge-symmetry-breaking forces can be measured in elastic $n\ensuremath{-}p$ scattering. We find that a term in the one-pion exchange potential arising from the neutron-proton mass difference is dominant. This, together with single-photon exchange, gives a result in agreement with a recent precise measurement made at TRIUMF. Other shorter-ranged effects associated with rho exchange, meson mixing, two-pion exchanges, and quark interactions give smaller contributions.