Showing papers on "Meson published in 2004"
TL;DR: The narrow charmonium state near 3872 MeV reported by the Belle Collaboration and confirmed by CDF lies almost exactly at the D 0 D ∗0 threshold as mentioned in this paper.
401 citations
TL;DR: In this paper, the Lagrangian density in the relativistic mean field (RMF) theory has been modeled in a microscopic way, which is essential to unify the description of nuclei from light to heavy regions with one effective interaction.
Abstract: New parameter sets for the Lagrangian density in the relativistic mean field (RMF) theory, PK1 with nonlinear sigma- and omega-meson self-coupling, PK1R with nonlinear sigma-, omega-, and rho-meson self-coupling, and PKDD with the density-dependent meson-nucleon coupling are proposed. They are able to provide an excellent description not only for the properties of nuclear matter but also for the nuclei in and far from the valley of beta stability. For the first time in the parametrization of the RMF Lagrangian density, the center-of-mass correction is treated by a microscopic way, which is essential to unify the description of nuclei from light to heavy regions with one effective interaction.
313 citations
TL;DR: In this paper, the authors discuss theoretical predictions for the existence of exotic nonquark-model mesons and review prominent experimental candidates, and conclude that some of these states exist, offer their views and discuss crucial issues that need to be investigated both theoretically and experimentally.
298 citations
TL;DR: In this paper, the effects of charm-quark interactions in a quark-gluon plasma on the production of D and J / ψ mesons in high-energy heavy-ion collisions were investigated.
283 citations
TL;DR: Light scalar mesons are found to fit rather well a diquark-antidiquark description, and the resulting nonet obeys mass formulas which respect, to a good extent, the Okubo-Zweig-Iizuka (OZI) rule.
Abstract: Light scalar mesons are found to fit rather well a diquark-antidiquark description. The resulting nonet obeys mass formulas which respect, to a good extent, the Okubo-Zweig-Iizuka (OZI) rule. OZI allowed strong decays are reasonably reproduced by a single amplitude describing the switch of a $q\overline{q}$ pair, which transforms the state into two colorless pseudoscalar mesons. Predicted heavy states with one or more quarks replaced by charm or beauty are briefly described; they should give rise to narrow states with exotic quantum numbers.
281 citations
TL;DR: In this article, the decay constants and form factors of the ground-state s-wave and low-lying p-wave mesons within a covariant light-front approach were studied.
Abstract: We study the decay constants and form factors of the ground-state s-wave and low-lying p-wave mesons within a covariant light-front approach. Numerical results of the form factors for transitions between a heavy pseudoscalar meson and an s-wave or p-wave meson and their momentum dependence are presented in detail. In particular, form factors for heavy-to-light and B to D** transitions, where D** denotes generically a p-wave charmed meson, are compared with other model calculations. The experimental measurements of the decays B^- to D** pi^- and B to D D**_s are employed to test the decay constants of D**_s and the B to D** transition form factors. The heavy quark limit behavior of the decay constants and form factors is examined and it is found that the requirement of heavy quark symmetry is satisfied. The universal Isgur-Wise (IW) functions, one for s-wave to s-wave and two for s-wave to p-wave transitions, are obtained. The values of IW functions at zero recoil and their slope parameters can be used to test the Bjorken and Uraltsev sum rules.
278 citations
TL;DR: In this paper, the thermal emission of photons from hot and dense strongly interacting hadronic matter at temperatures close to the expected phase transition to the quark-gluon plasma (QGP) was studied.
Abstract: We study the thermal emission of photons from hot and dense strongly interacting hadronic matter at temperatures close to the expected phase transition to the quark-gluon plasma (QGP). Earlier calculations of photon radiation from ensembles of interacting mesons are reexamined with additional constraints, including new production channels as well as an assessment of hadronic form factor effects. Whereas strangeness-induced photon yields turn out to be moderate, the hitherto not considered $t$-channel exchange of $\ensuremath{\omega}$ mesons is found to contribute appreciably for photon energies above $\ensuremath{\sim}1.5\phantom{\rule{0.3em}{0ex}}\text{GeV}$. The role of baryonic effects is assessed using existing many-body calculations of lepton pair production. We argue that our combined results constitute a rather realistic emission rate, appropriate for applications in relativistic heavy-ion collisions. Supplemented with recent evaluations of QGP emission, and an estimate for primordial (hard) production, we compute photon spectra at Super Proton Synchrotron (SPS), Relativistic Heavy Ion Collider (RHIC), and Large Hadron Collider (LHC) energies.
268 citations
TL;DR: In this article, an improved Kogut-Susskind quark action was extended to a smaller lattice spacing, approximately 0.09 fm, and the dependence of computed quantities on the spatial size of the lattice, on the numerical precision in the computations, and on the step size used in the numerical integrations was examined.
Abstract: We have extended our program of QCD simulations with an improved Kogut-Susskind quark action to a smaller lattice spacing, approximately 0.09 fm. Also, the simulations with $a\ensuremath{\approx}0.12$ fm have been extended to smaller quark masses. In this paper we describe the new simulations and computations of the static quark potential and light hadron spectrum. These results give information about the remaining dependences on the lattice spacing. We examine the dependence of computed quantities on the spatial size of the lattice, on the numerical precision in the computations, and on the step size used in the numerical integrations. We examine the effects of autocorrelations in ``simulation time'' on the potential and spectrum. We see possible effects of decays, or coupling to two-meson states in the ${0}^{++}$ and ${1}^{+}$ meson propagators. A state consistent with $\ensuremath{\pi}+K$ is seen as a ``parity partner'' in the Goldstone kaon propagator, and we make a preliminary mass computation for a radially excited ${0}^{\ensuremath{-}}$ meson.
247 citations
TL;DR: In this paper, a parameter-free prediction is obtained for the scattering of Goldstone bosons off heavy-light pseudo-scalar and vector mesons in terms of the non-linear chiral SU(3) Lagrangian.
226 citations
TL;DR: In this paper, the meson resonances with quantum numbers JP = 1+ in terms of the chiral SU(3) Lagrangian were studied and a parameter-free prediction was obtained for the scattering of Goldstone bosons off vector mesons with JP=1− once they insist on approximate crossing symmetry of the unitarized scattering amplitude.
224 citations
TL;DR: In this article, the spectrum of the charm-beauty mesons using the relativized quark model was calculated using the wave functions from this model and the radiative widths of excited cb states were estimated using the Kuang-Yan approach.
Abstract: We calculate the spectrum of the charm-beauty mesons using the relativized quark model. Using the wave functions from this model we compute the radiative widths of excited cb states. The hadronic transition rates between cb states are estimated using the Kuang-Yan approach and are combined with the radiative widths to give estimates of the relative branching ratios. These results are combined with production rates at the Tevatron and the LHC to suggest promising signals for excited B{sub c} states. Our results are compared with other models to gauge the reliability of the predictions and point out differences.
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TL;DR: In this paper, the authors reviewed the extensive spectrum of light nonstrange qbar-q states up to a mass of 2400 MeV from Crystal Barrel and PS172 data on pbar-p -> Resonance -> A + B in 17 final states.
Abstract: This report reviews the extensive spectrum of light non-strange qbar-q states up to a mass of 2400 MeV from Crystal Barrel and PS172 data on pbar-p -> Resonance -> A + B in 17 final states. For I=0, C=+1, the spectrum is complete and very secure. Glueball candidates fo(1500), fo(2100), f_2(1950) and eta(2190) are reviewed and also hybrid candidates eta_2(1870) and pi_2(1880). A fourth category of anomalously light 0+ mesons is made of sigma(540), kappa(750), a_0(980) and f_0(980).
TL;DR: In this paper, the authors review the status of the present theoretical understanding of nucleon-nucleon reactions with special emphasis on model-independent methods and discuss the physical questions that can be addressed by studying them in the various reaction channels.
TL;DR: In this article, the authors investigated the density dependence of the symmetry energy in a relativistic description by decomposing the isovector mean field into contributions with different Lorentz covariant properties.
TL;DR: In this article, the exclusive electroproduction of J/psi mesons, ep --> epJ/psI, has been studied with the ZEUS detector at HERA for virtualities of the exchanged photon in the ranges 0.15 < Q(2) < 0.8 GeV2.
TL;DR: In this article, it was proposed that measuring the 3 π J / ψ, γ J /π�, π ψ ′, K ¯ K *, and πρ decay modes of the X will serve as a definitive diagnostic of the molecule hypothesis.
TL;DR: In this paper, the authors present a unified derivation of most of the phenomenological approaches being used to extract the resonance parameters from the data, and the analyses of π and η production data and the resulting transition form factors for the Δ(1232)P33, N(1535)S11, N 1440)P11, and N 1520)D13 resonances are discussed in detail.
Abstract: Recent experimental and theoretical advances in investigating electromagnetic meson production reactions in the nucleon resonance region are reviewed. We give a description of current experimental facilities with electron and photon beams and present a unified derivation of most of the phenomenological approaches being used to extract the resonance parameters from the data. The analyses of π and η production data and the resulting transition form factors for the Δ(1232)P33, N(1535)S11, N(1440)P11, and N(1520)D13 resonances are discussed in detail. The status of our understanding of the reactions with production of two pions, kaons, and vector mesons is also reviewed.
TL;DR: Goldstone modes are the only pseudoscalar mesons with a nonzero leptonic decay constant in the chiral limit when chiral symmetry is dynamically broken as mentioned in this paper.
Abstract: Goldstone modes are the only pseudoscalar mesons to possess a nonzero leptonic decay constant in the chiral limit when chiral symmetry is dynamically broken. The decay constants of their radial excitations vanish. These features and aspects of their impact on the meson spectrum are illustrated using a manifestly covariant and symmetry-preserving model of the kernels in the gap and Bethe-Salpeter equations.
TL;DR: In this article, heavy-light meson resonances with quantum numbers JP=0+ and JP=1+ in terms of the non-linear chiral SU(3) Lagrangian were studied.
TL;DR: In this paper, the authors derived a dispersion relation based on heavy quark effective theory that relates the mass difference between two neutral D meson mass eigenstates to an integral of the width difference of heavy mesons.
Abstract: We study the Standard Model prediction for the mass difference between the two neutral D meson mass eigenstates, $\Delta m$. We derive a dispersion relation based on heavy quark effective theory that relates $\Delta m$ to an integral of the width difference of heavy mesons, $\Delta\Gamma$, over varying values of the heavy meson mass. Modeling the $m_D$-dependence of certain D decay partial widths, we investigate the effects of SU(3) breaking from phase space on the mass difference. We find that $\Delta m$ may be comparable in magnitude to $\Delta\Gamma$ in the Standard Model.
TL;DR: In this article, a detailed comparison of a variety of predictions for diffractive light vector meson production with the data collected at the DESY HERA collider was performed within a dipole model framework and make use of different models for the meson light-cone wave function.
Abstract: We present a detailed comparison of a variety of predictions for diffractive light vector meson production with the data collected at the DESY HERA collider. All our calculations are performed within a dipole model framework and make use of different models for the meson light-cone wave function. There are no free parameters in any of the scenarios we consider. Generally we find good agreement with the data using rather simple Gaussian motivated wave functions in conjunction with dipole cross sections which have been fitted to other data.
TL;DR: In this paper, the authors present results from quenched spectroscopy calculations with the parametrized fixed-point and the chirally improved Dirac operators for small quark masses and explore pseudoscalar-mass to vector-mass ratios down to 0.28.
TL;DR: In this paper, a detailed comparison of a variety of predictions for diffractive light vector meson production with the data collected at the DESY HERA collider was performed within a dipole model framework and make use of different models for the meson light-cone wave function.
Abstract: We present a detailed comparison of a variety of predictions for diffractive light vector meson production with the data collected at the DESY HERA collider All our calculations are performed within a dipole model framework and make use of different models for the meson light-cone wave function There are no free parameters in any of the scenarios we consider Generally we find good agreement with the data using rather simple Gaussian motivated wave functions in conjunction with dipole cross sections which have been fitted to other data
TL;DR: In this article, the authors investigate four-body states with only charm quarks and present a net binding analysis to determine if the resulting states are stable against breakup into a pair of $c\overline{c}$ mesons.
Abstract: We investigate four-body states with only charm quarks. Working in a large but finite oscillator basis, we present a net binding analysis to determine if the resulting states are stable against breakup into a pair of $c\overline{c}$ mesons. We find several close-lying bound states in the two models we examine.
TL;DR: In this article, the gravity dual description of mesons for a three-dimensional super Yang-Mills theory with fundamental matter was established, and the dictionary between meson-like operators and supergravity fluctuations in the corresponding near-horizon geometry was discussed.
Abstract: In view of extending gauge/gravity dualities with flavour beyond the probe approximation, we establish the gravity dual description of mesons for a three-dimensional super Yang-Mills theory with fundamental matter. For this purpose we consider the fully backreacted D2/D6 brane solution of Cherkis and Hashimoto in an approximation due to Pelc and Siebelink. The low-energy field theory is the IR fixed point theory of three-dimensional N=4 SU(N_c) super Yang-Mills with N_f fundamental fields, which we consider in a large N_c and N_f limit with N_f/N_c finite and fixed. We discuss the dictionary between meson-like operators and supergravity fluctuations in the corresponding near-horizon geometry. In particular, we find that the mesons are dual to the low-energy limit of closed string states. In analogy to computations of glueball mass spectra, we calculate the mass of the lowest-lying meson and find that it depends linearly on the quark mass.
TL;DR: In this paper, the authors considered constraints on the momentum fraction of the meson carried by the strange quark that follow from exact operator identities, similar to those for the divergence of the quark part of the QCD energy-momentum tensor.
Abstract: We consider constraints on the momentum fraction of the $K$ and ${K}^{*}$ meson carried by the strange quark that follow from exact operator identities, similar to those for the divergence of the quark part of the QCD energy-momentum tensor. The existing QCD sum rule estimates are reanalyzed in this context. Our conclusions essentially support the constituent quark-model picture where the momentum fraction is roughly proportional to the constituent quark mass, but the asymmetry turns out to be smaller compared to the naive quark-model estimates. As a by-product of this study, we calculate the SU(3)-breaking quark-antiquark-gluon matrix elements that determine the leading conformal spin contributions to the asymmetry in twist-four distribution amplitudes of strange mesons $K$ and ${K}^{*}$, and also update the estimate for the SU(3) breaking for the quark-antiquark-gluon vacuum condensate.
TL;DR: In this article, the authors studied the process of exclusive heavy vector meson photoproduction in the framework of QCD factorization and showed that the amplitude factorizes in a convolution of a perturbatively calculable hard-scattering amplitude with the generalized parton densities and the nonrelativistic QCD matrix element.
Abstract: The process of exclusive heavy vector meson photoproduction, $\gamma p \to V p$
, is studied in the framework of QCD factorization. The mass of the produced meson, $V = \Upsilon$
or $J/\Psi$
, provides a hard scale for the process. We demonstrate that, in the heavy quark limit and at the one-loop order in perturbation theory, the amplitude factorizes in a convolution of a perturbatively calculable hard-scattering amplitude with the generalized parton densities and the non-relativistic QCD matrix element $\langle O_1\rangle_{V}$
. We evaluate the hard-scattering amplitude at one-loop order and compare the data with theoretical predictions using an available model for generalized parton distributions.
TL;DR: Five helicity distributions including those for three sea quark flavors were extracted from data extracted together with reanalyzed previous data for identified pions from a hydrogen target, consistent with zero for all three sea flavors.
Abstract: Double-spin asymmetries of semiinclusive cross sections for the production of identified pions and kaons have been measured in deep inelastic scattering of polarized positrons on a polarized deuterium target. Five helicity distributions including those for three sea quark flavors were extracted from these data together with reanalyzed previous data for identified pions from a hydrogen target. These distributions are consistent with zero for all three sea flavors. A recently predicted flavor asymmetry in the polarization of the light quark sea appears to be disfavored by the data.
TL;DR: In this article, the authors provide a string theoretical derivation via the gauge/string correspondence of a phenomenological model describing the meson as rotating point-like massive particles connected by a flux string.
Abstract: We discuss Regge trajectories of dynamical mesons in large-N_c QCD, using the supergravity background describing N_c D4-branes compactified on a thermal circle. The flavor degrees of freedom arise from the addition of N_f<
TL;DR: In this article, a method to compute Euclidean meson two-point functions in lattice QCD is described and tested, where the contribution from the low-lying eigenmodes of the Dirac operator is averaged over all positions of the quark sources.