Showing papers on "Meson published in 1984"
TL;DR: The main ideas, methods and results in the investigation of the asymptotic behaviour of exclusive processes are reviewed in this paper, where power behavior and its dependence on hadron quantum numbers, logarithmic corrections and properties of nonperturbative hadronic wave functions are discussed.
843 citations
TL;DR: In this paper, phenomenological Lagrangians are obtained for interactions of scalar, pseudoscalar, vector, and axial vector meson nonets, and the widths of various meson decays are calculated.
234 citations
TL;DR: In this article, vector mesons in a chiral lagrangian were introduced to stabilize the chiral solitons and the static properties of baryons in this model were computed.
200 citations
TL;DR: In this paper, the effect of SU(3) constraints on baryon-baryon coupling constants was analyzed in the context of meson exchange with nuclei, and it was shown how to construct the effective baryons-nucleon interaction matrix (G-matrix).
170 citations
TL;DR: In this article, a linear σ-model is used to describe the N and Δ as three quarks interacting via σ and π mesons, and the effects of confinement are neglected.
142 citations
TL;DR: In this paper, the authors present the next-next-to-leading three-loop perturbative QCD corrections to the (pseudo) scalar quark current correlator.
88 citations
TL;DR: In this paper, a general background field method is presented to compute operator product expansions in the framework of QCD sum rules for operators coupling to hybrid mesons, and the masses and couplings of quark-antiquark-gluon states with JPC = 1−+, 1+−, 0++, 0−− and I = 0, 1.
84 citations
TL;DR: In this paper, deep-inelastic scattering from mesons responsible for nuclear binding has been investigated and it is shown that the magnitude of the effect at small x cannot be quantitatively characterized unless the meson structure function is assumed to have an enhanced pion density of about 0.4 extra pions per nucleon (roughly three times that provided by conventional nuclear models).
Abstract: Recent data indicate that quark densities in a high-A nucleus differ significantly from those measured in the free-nucleon case. We examine whether this effect can be explained in terms of deep-inelastic scattering from mesons responsible for nuclear binding. Although features of the data are reproduced qualitatively, we are unable to approach a quantitative description of the magnitude of the experimental effect at small x unless we postulate an enhanced pion density of about 0.4 extra pions per nucleon (roughly three times that provided by conventional nuclear models), and/or make assumptions about the small-x behavior of the meson structure function which are inconsistent with available data. These conclusions are insensitive to the manner in which we impose momentum conservation. The slope of the ratio of structure functions vs x is reproduced easily in the range 0.05
82 citations
TL;DR: In this paper, the momentum spectrum of leptons produced in semileptonic B-meson decays was used to set a 90%-confidence-level upper limit on GAMMA(b..-->..ul..nu..)/GAMMA( b..-->.cl..nu).
Abstract: We have used the momentum spectrum of leptons produced in semileptonic B-meson decays to set a 90%-confidence-level upper limit on GAMMA(b..-->..ul..nu..)/GAMMA(b..-->..cl..nu..) of 4%. We also measure the semileptonic branching fractions of the B meson to be (12.0 +- 0.7 +- 0.5)% for electrons and (10.8 +- 0.6 +- 1.0)% for muons.
71 citations
TL;DR: The relation between four-fermion operators on the lattice and the corresponding operators in the continuum is computed at first order in perturbation theory as mentioned in this paper, and a first evaluation of the matrix elements of these operators, which are essential for theoretical predictions for weak non-leptonic decays such as the ΔT = 1 2 and the Δt = 3 2 rates for K meson decays, has been recently performed using Monte Carlo techniques.
67 citations
TL;DR: In this paper, the meson exchange current operators of main importance for the electromagnetic properties and reactions of nuclei at low and intermediate energies are described, and the importance of the underlying theoretical framework, phenomenological Lagrangians constrained by chiral invariance requirements, is emphasized.
TL;DR: In this article, the authors reported the results of hadron mass calculations in the valence (quenched) approximation on an 8 3 × 16 lattice and repeated these calculations at two points of the same string tension in the plane of the fundamental and adjoint couplings.
TL;DR: In this paper, the authors used data from the SLAC storage ring PEP to study the production of charged hadrons and compared the performance of various hadronization models with the data.
Abstract: Data from the Time Projection Chamber at the SLAC storage ring PEP have been used to study the inclusive production of charged hadrons. Particles were identified by simultaneous dE/dx and momentum measurements. Cross sections and particle fractions for pi +/-, k+/-, and p(anti-p) are given as a function of several variables. Predictions of various hadronization models are compared to the data. A comparison is made with other fragmentation processes.
01 Jan 1984
TL;DR: In this article, it was shown that effects which are preasymptotic in the mass of the heavy quark in nonleptonic weak decays of charmed particles lead to the experimentally observed hierarchy of lifetimes tau(.. lambda../sub c//sup +/).. us in the case of.. lambda../sup +//sub c/ decay.
Abstract: It is shown that effects which are preasymptotic in the mass of the heavy quark in nonleptonic weak decays of charmed particles lead to the experimentally observed hierarchy of lifetimes tau(..lambda../sub c//sup +/).. us in the case of ..lambda../sup +//sub c/ decay.
TL;DR: In this paper, two-body Dirac equations are used to make the naive quark model fully relativistic, and a covariant generalization of Richardson's static quark potential produces a surprisingly good one-parameter relativism fit to the meson spectrum.
Abstract: We use two-body Dirac equations (derived from Dirac's constraint mechanics and super-symmetry) to make the naive quark model fully relativistic. Our covariant equations incorporate not only relativistic kinematics but also dynamical recoil effects that generalize Breit corrections to forms that have well-defined quantum short-distance behavior. In these equations, a crude but covariant generalization of Richardson's static quark potential produces a surprisingly good one-parameter relativistic fit to the meson spectrum.
TL;DR: In this paper, it was shown that energy and transverse momentum distributions of top-meson decay products are effected and eventually enhanced or depleted by a factor between 0.5 and 1.5.
TL;DR: In this article, the scalar meson G(1590) is considered as a possible glueball and the decay mechanism, characteristic of a glueball, is proposed (the discolouring of gluons by glusons) which allows one to understand the increase ofG→ηη decay rate, as compared to the decaysG→πππ andG→K\(\bar K\) observed in the experiment.
Abstract: The scalar mesonG(1590) is considered as a possible glueball. The decay mechanism, characteristic of a glueball, is proposed (the discolouring of gluons by gluons) which allows one to understand the increase ofG→ηη decay rate, as compared to the decaysG→ππ andG→K\(\bar K\) observed in the experiment. It is proposed to measure the ratio of branching ratiosR=BR(G→ηη′)/BR(G→ηη), which is sensitive to the gluon content ofG(1590). In the one-pion exchange model the predictedR values are within the range:2≲R≲3.7.
CERN1
TL;DR: In this article, the partial widths of the η-meson were measured in a high accuracy experiment made at the IHEP accelerator with the hodoscope electromagnetic spectrometer GAMS-2000.
Abstract: The partial widths of η-meson decays η→2γ, η→3π0 and η→π0γγ have been measured in a high accuracy experiment made at the IHEP accelerator with the hodoscope electromagnetic spectrometer GAMS-2000. An upper limit has been determined for the 3γ channel. The Dalitz plot of the η decay into 3π0 shows that the matrix element does not depend on the pion energy.
Heidelberg University1, University of Kansas2, Lund University3, University of South Carolina4, California Institute of Technology5, University of Cape Town6, Carnegie Mellon University7, Polish Academy of Sciences8, University of Erlangen-Nuremberg9, University of Florence10, University of Hamburg11, Harvard University12, Radboud University Nijmegen13, Princeton University14, Stanford University15, University of Würzburg16
TL;DR: The e + e − − -storage ring DORIS II provides polarized beams with polarizations up to 80% in the energy range of the ϒ ′ meson as discussed by the authors.
TL;DR: In this paper, the authors reported measurements of pp total cross sections from 388 to 599 MeV/c in small momentum steps and reported statistical errors are typically ± 0.4% and the normalisation uncertainty is ±0.7%.
TL;DR: In this paper, the axial vector current remains finite in the limit as the bag radius, R, goes to zero and the chiral angle, θ ( R), goes to π.
TL;DR: In this article, a high-statistics study of psi decays into baryon final states has been done with the Mark II detector at SPEAR, and a detailed test of baryons-antibaryon decay modes is presented.
Abstract: A high-statistics study of psi decays into baryon final states has been done with the Mark II detector at SPEAR. A detailed test of baryon-antibaryon decay modes is presented. Substantial resonance formation is observed in multibody decays of the psi involving baryons. Branching ratios for a large number of decay modes are given, including the radiative decay psi..-->..pp-bar..gamma... The flavor-SU(3)-forbidden decays psi..--> sigma../sup + -/(1385)Sigma-bar /sup - +/+charge conjugate are observed with substantial branching ratios.
TL;DR: In this paper, the ω → 3 π contact term was determined based on the low-energy theorems of broken chiral symmetry, which are compatible with calculations based on effective vertices and vector-meson dominance.
TL;DR: In this article, the authors search for flavor-changing neutral-current weak decays of the b quark and find R/sub B/(b..-->..l/sup +/l/Sup -/X) < 0.31 at 90% confidence level.
Abstract: We have searched for flavor-changing neutral-current weak decays of the b quark and find R/sub B/(b..-->..l/sup +/l/sup -/X)<0.31 at 90% confidence level. This limit excludes models with the b quark in a left-handed isosinglet. We also place limits on the ratio of the B/sup + -/ and B/sup 0/ semileptonic branching fractions and on B/sup 0/B-bar /sup 0/ mixing.
TL;DR: In this article, the authors presented a new evaluation of the two-point function built from the colourless operators g Ψ λ a γ v (γ 5 )ΨF μv a.
TL;DR: In this article, the authors apply the knowledge about the short distance structure of baryon wave functions gleaned from QCD form factor calculations nd the J gY → p p decay rate to calculate the p → e + π 0 decay rate in minimal SU(5) and other grand unified theories for a specified value of the heavy vector boson mass m X.
TL;DR: In this paper, the off-diagonal two-point correlation function responsible for the gluonium-meson mixing was evaluated, including the leading nonperturbative lowest dimension vacuum condensate contributions.
TL;DR: A detailed relativistic calculation of pp → πd is presented in this paper, where the leading graph is the exchange of a nucleon and a pion and the πN amplitudes, including off-shell information, are input.