Showing papers on "Meson published in 1991"
TL;DR: In this article, the Nambu and Jona-Lasinio model with three quark flavors, based on the SU(3)L ⊗ SU( 3)R ⊆ U(1)V symmetry of QCD, is reviewed.
714 citations
TL;DR: In this article, the time-dependent decay rates of the three processes B d 0 → D 0 K s, D 0 k s, and D 1 0 K S, where D10 is a neutral D meson CP-eigenstate, were derived from the unitarity triangle of the Cabibbo-Kobayashi-Maskawa matrix.
339 citations
TL;DR: It has recently been shown that hadrons containing a single heavy quark exhibit a new flavor-spin symmetry of QCD, and the implications for the masses and strong decay widths of such hadrons are discussed.
Abstract: It has recently been shown that hadrons containing a single heavy quark exhibit a new flavor-spin symmetry of QCD. We discuss the implications of this symmetry for the masses and strong decay widths of such hadrons.
332 citations
Rice University1, University of Iowa2, Fermilab3, Kyoto University4, Argonne National Laboratory5, Hiroshima University6, Northeastern State University7, Northwestern University8, University of Udine9, University of Trieste10, University of Messina11, Kyoto Sangyo University12, Okayama University13, Los Alamos National Laboratory14, Osaka City University15
TL;DR: In this article, the analyzing power in inclusive charged pion production has been measured using the 200 GeV Fermilab polarized proton beam, and it was shown that at large x(F) the transverse spin of the proton is correlated with that of its quark constituents.
275 citations
TL;DR: It is found that, even for {ital B} mesons, the tensor interactions play an important role in the spectroscopy and the {ital m}{sub {ital Q}}{r arrow}{infinity} has not yet been reached, and it is concluded that further experimental study of the decay properties of the{ital D}{sub 1} meson is important to the understanding of the mixing mechanism.
Abstract: We present the results of a quark model study of $L=1$ mesons with one heavy quark. We give the masses of these states as predicted by the relativized quark model and the decay properties as calculated using both the pseudoscalar emission model and the flux-tube-breaking model. We examine the idealized limit of one infinitely massive quark and one light quark and discuss our results in this context as a guide to what can be learned from the study of these states. We find that, even for $B$ mesons, the tensor interactions play an important role in the spectroscopy and the ${m}_{Q}\ensuremath{\rightarrow}\ensuremath{\infty}$ has not yet been reached. We conclude that further experimental study of the decay properties of the ${D}_{1}$ mesons is important to the understanding of the $^{3}P_{1}\ensuremath{-}^{1}P_{1}$ mixing mechanism.
275 citations
TL;DR: In this paper, the Gounaris-Sakurai formula was generalized to finite temperature and the mass and width of both transverse and longitudinal ϱ-mesons increase with temperature, but temperature effects are still relatively small up to T = 150 MeV.
233 citations
TL;DR: In this paper, it was shown that factorization holds perturbatively in QCD, provided one looks in the appropriate kinematic regime, which includes all orders in the loop expansion.
217 citations
TL;DR: In this article, a nonrelativistic reformulation of the heavy-quark dynamics that is systematically developed starting from the Dirac theory is presented. But this method is not suitable for lattice QCD.
Abstract: We present a new technique for analyzing heavy-quark bound states in lattice QCD. The method is based upon a nonrelativistic reformulation of the heavy-quark dynamics that is systematically developed starting from the Dirac theory. It is far superior to traditional relativistic techniques, as we illustrate in a numerical study of the $\ensuremath{\Upsilon}$ and $\ensuremath{\psi}$ meson families.
197 citations
01 Jun 1991
TL;DR: In this paper, the authors summarized progress during the past year in the following areas of research: Pion double charge exchange, including studies of the contribution of meson exchange currents and the roles of chiral symmetry and of vector mesons.
Abstract: This report summarizes progress during the past year in the following areas of research: Pion double charge exchange, including studies of the contribution of meson exchange currents and the roles of chiral symmetry and of vector mesons. The possibility of bound states of two hyperons and the H dibaryon. Many body theory, including studies of nuclear scattering in a quark cluster model, nuclear structure calculations, and a one-dimensional model with charged'' bosons. Statistical nuclear spectroscopy, including formalism and programs for state densities and partition functions, single-state occupancies and spin-cut off factors, measures for symmetry breaking, and the relationship between statistical and shell-model spectroscopy.
194 citations
TL;DR: In this article, the authors report on a study of particle production in pp-interactions at 400 GeV/c. The data are based on 472 K reconstructed events recorded in the NA 27 experiment using the LEBC-EHS facility at CERN.
Abstract: We report on a study of inclusive particle production in pp-interactions at 400 GeV/c. The data are based on 472 K reconstructed events recorded in the NA 27 experiment using the LEBC-EHS facility at CERN. The production cross sections are determined of pseudo scalar (π±,0, η andK±), scalar (f0(975)), vector (ρ±,0(770), ω(783), ϕ(1020),K*0(892), and\(\bar K^{ * 0} \)(892)), and tensorf0 mesons, of protons and antiprotons, and theΔ++,+,0(1232), and Λ(1520) baryon resonances in the forward hemisphere of the center of mass system, as well as longitudinal and transverse momentum distributions. The results are compared with predictions of the FRITIOF model and with other experimental data.
178 citations
TL;DR: A consistent picture of the {ital q{bar q}} system emerges which should allow a reliable treatment of electroweak phenomena in the heavy-meson sector also.
Abstract: We investigate the predictive power of a relativistic constituent-quark model of electroweak properties of pseudoscalar and vector mesons in the {ital u}-, {ital d}-, {ital s}-quark sector. The rates for radiative and weak decay processes and electromagnetic form factors for charged and neutral pseudoscalar mesons are calculated and compared with experiment. This analysis determines the values of the angles for {eta}-{eta}{prime} and {omega}-{phi} mixing, and also the Kobayashi-Maskawa matrix element {ital V}{sub {ital u}{ital s}}. A consistent picture of the {ital q{bar q}} system emerges which should allow a reliable treatment of electroweak phenomena in the heavy-meson sector also.
TL;DR: In this article, the decay rates at zero recoil are fixed by a normalization condition for the hadronic form factors, which, in general, is violated by 1/mQ corrections.
TL;DR: In this article, the authors review the description of the electromagnetic properties of baryons with explicit reference to the quark degrees of freedom and present a theoretical framework for interpreting the experimental baryon data, including photon-proton scattering and pion photoproduction.
Abstract: The description of the electromagnetic properties of baryons with explicit reference to the quark degrees of freedom is reviewed. After a short discussion of the available phenomenological information, such as magnetic moments, form factors and photoexcitation amplitudes, the constituent quark model in the potential approach is introduced and the consequent description of the baryon spectrum is briefly discussed. The model is then systematically used as a theoretical framework for the interpretation of the experimental baryon data, including photon-proton scattering and pion photoproduction, and for the discussion of recent studies of the electromagnetic properties of few-nucleon systems. In particular, the reformulation of meson exchange currents in terms of quark degrees of freedom is reported and the results of various quark approaches to the form factors are presented. Finally, some recent improvements and future developments are briefly discussed.
TL;DR: In this paper, a high statistics computation of the decay constant ƒ B is presented to study scaling and finite size effects, and the authors observe the scaling violation in the static approximation to be 15% between β = 5.7 and 6.0 even beyond the D-meson mass.
TL;DR: In this paper, the decay constant of the B-meson, ƒB, on a 102 × 20 × 40 lattice at β = 6.0, with Wilson fermions, using 30 gauge field configurations, generated in the quenched approximation.
TL;DR: In this paper, the anomalous dimension and the first-order coefficient function of weak-interaction currents in the heavy-quark effective field theory were calculated, together with the two-loop QCD β-function, and these quantities form the complete sub-leading logarithmic corrections to the mass factorization of weak form factors.
TL;DR: In this paper, a relativistic meson exchange approach to the pion-nucleon interaction is developed using a three-dimensional relativistically two-body propagator and the results using different propagators compared.
TL;DR: Using the leading operators in the chiral lagrangian for meson-baryon interactions (at low momentum) and treating the meson fields classically, Kaplan and Nelson have observed, using numerical methods, that a charged kaon condensate forms at several times nuclear density.
TL;DR: In this paper, a complete calculation of the leading logarithmic QCD corrections to the effective hamiltonian for the b→sγ decay is presented, which is then applied to find the inclusive branching ratio for the weak radiative B -meson decay.
TL;DR: A general formalism is presented for calculating the difference between the partial decay rates of a particle and antiparticle based on invariance and unitarity and it is compared to the standard method using penguin graphs.
Abstract: The $\mathrm{CP}$-violating difference between the partial decay rates of a particle and antiparticle depends on final-state interactions. A general formalism is presented for calculating this difference based on $\mathrm{CPT}$ invariance and unitarity. Applications are given to $B$ decays and the formalism is compared to the standard method using penguin graphs.
TL;DR: In this article, the pp and pn η-production cross sections were calculated starting from an effective one-boson exchange model and unknown coupling constants were fitted to the elastic nucleon-nucleon scattering and to the decay rates of the N∗ (1535) and the pπ− → nη reaction.
TL;DR: A set of coupled transport equations for the phase-space distribution functions of nucleons, deltas, and pions is solved with the test particle method to study pion production in relativistic heavy ion collisions and the experimentally observed concave shape of the pion spectra is well reproduced.
Abstract: A set of coupled transport equations for the phase-space distribution functions of nucleons, deltas, and pions is solved with the test particle method to study pion production in relativistic heavy ion collisions. The experimentally observed concave shape of the pion spectra is well reproduced. The mechanism that causes the concave shape of the pion spectra is found to be due to the different contributions of the delta resonance produced during the early and the late stages of the heavy ion collision and due to the energy dependence of the pion and delta absorption cross sections. The dependence of the shape of the pion spectra on beam energy, target and projectile mass, and impact parameter is also studied. An approximate scaling function for the shape parameter of the pion spectra is found.
TL;DR: In this paper, the total cross section of the pp→K + Λ p and pp→k + Σ N reactions and the kaon spectra are fairly well accounted for by a meson exchange model which includes final state interactions in the coupled hyperon-nucleon channels.
TL;DR: In this paper, an experimentally detectable signal for K meson modification in hot hadronic matter, produced in high energy collisions, is presented. But the effect of meson modifications on the φ width Γ φ by a factor 2-3 is not discussed.
TL;DR: In this article, the energy momentum tensor to order 4 in chiral perturbation theory was calculated and new terms not present in previous work entered the effective Lagrangian.
Abstract: We calculate the energy momentum tensor to orderE4 in chiral perturbation theory. New terms not present in previous work enter the effective Lagrangian. We describe these and estimate the values of the new coupling constants, using the results of a disperisve analysis of the π andK energy momentum tensors and relying on tensor meson dominance for the spin two component. In addition, we compare our findings with the predictions of known scalar meson dominance models of the conformal anomaly.
TL;DR: In this paper, a meson exchange model, which includes final-state interactions, leads to a fair account for the scarcely available experimental cross sections of the pp → ppη and np → d η reactions.
TL;DR: A model for the nucleon-antinucleon interaction is presented, which is based on meson-baryon dynamics, and results for cross sections and polarization data are compared with a phenomenological treatment of annihilation based on a simple, state- and energy-independent optical potential.
Abstract: A model for the nucleon-antinucleon interaction is presented, which is based on meson-baryon dynamics. The elastic part is the {ital G}-parity transform of the Bonn {ital NN} potential; annihilation is accounted for by microscopic baryon-exchange processes with two-meson intermediate states involving {pi}, {rho}, {sigma}, {omega}, {delta}, K, and {ital K}{sup *}. Results for cross sections and polarization data are compared with a phenomenological treatment of annihilation based on a simple, state- and energy-independent optical potential.
TL;DR: The equations give an analytic solution for a zero-mass pseudoscalar bound state in the case of exact chiral symmetry, and also reduce to the familiar, highly successful nonrelativistic linear potential models in the limit of heavy-quark mass and lightly bound systems.
Abstract: We introduce a new model of mesons as quark-antiquark bound states. The model is covariant, confining, and chirally symmetric. Our equations give an analytic solution for a zero-mass pseudoscalar bound state in the case of exact chiral symmetry, and also reduce to the familiar, highly successful nonrelativistic linear potential models in the limit of heavy-quark mass and lightly bound systems. In this fashion we are constructing a unified description of all the mesons from the {pi} through the {Upsilon}. Numerical solutions for other cases are also presented.
TL;DR: In this article, a relative suppression factor of an order of magnitude in certain diagrams was used to identify penguin contributions to B→Kη and B→kη′ decays as well as annihilation diagram contributions to corresponding D decays.
TL;DR: A gradual increase of ({ital dn}/{ital dy}){sub {ital K}}{sup +} per projectile nucleon is observed from {ital p}+Be to {italp}+Au to central Si-Au collisions, while pions show no significant increase.
Abstract: The production of {pi}{sup {plus minus}},{ital K}{sup {plus minus}},{ital p} has been measured in {ital p}+Be and {ital p}+Au collisions for comparison with central Si+Au collisions. The inverse slope parameters {ital T}{sub 0} obtained by an exponential fit to the invariant cross sections in transverse mass are found to be, {ital T}{sub 0}{sup {ital p},}{ital K+},{pi}{sup {pi}}{similar to}140--160 MeV in {ital p}+{ital A} collisions, whereas in central Si+Au collisions, {ital T}{sub 0}{sup {ital p},}{ital K+}{similar to}200--220 MeV {gt}{ital T}{sub 0}{sup {pi}{pi}}{similar to}140--160 MeV at midrapidity. The {pi}{sup {plus minus}} and {ital K}{sup +} distributions are shifted backwards in {ital p}+Au compared with {ital p}+Be. A gradual increase of ({ital dn}/{ital dy}){sub {ital K}}{sup +} per projectile nucleon is observed from {ital p}+Be to {ital p}+Au to central Si+Au collisions, while pions show no significant increase.