Showing papers on "Meson published in 1990"
TL;DR: In this paper, the authors present an extension of their earlier observations on symmetries in operation in the weak decays of heavy mesons containing a single heavy quark, which allow them to obtain absolutely normalized model-independent predictions in the heavy quarks limit of all of the form factors for the Q1 → Q2 induced weak pseudoscalar and pseudoscalar to vector transitions in terms of a single universal function ξ(t) with ξ (0) = 1.
883 citations
TL;DR: In this paper, a method is presented which allows a simple, selfconsistent solution of the Dirac equation for the deformed spinor fields of the nucleons and of the Klein-Gordon equation for deformed scalar and vector fields of mesons.
622 citations
TL;DR: The formalism, the potentials, and the results of this paper may also serve as a basis and a realistic starting point for systematic relativistic nuclear structure studies as well as for the investigation of further relativism many-body corrections and of contributions of higher order.
Abstract: The formalism for the Dirac-Brueckner approach to the nuclear many-body problem is described including its basis in relativistic two-nucleon scattering. A family of relativistic meson-exchange potentials is constructed which (apart from the usual coupling terms for heavy mesons) apply the pseudovector (gradient) coupling for the interaction of pseudoscalar mesons (\ensuremath{\pi},\ensuremath{\eta}) with nucleons. These potentials describe low-energy two-nucleon scattering and the deuteron data accurately. Using these potentials, the properties of nuclear matter are calculated in the Dirac-Brueckner-Hartree-Fock approximation, in which the empirical nuclear matter saturation is explained quantitatively. The effective two-body interaction in the nuclear matter medium (G matrix) is calculated directly in the nuclear matter rest frame. Thus, cumbersome transformations between the two-nucleon center-of-mass frame and the nuclear matter rest frame are avoided. Size and nature of relativistic effects included in the present approach are examined in detail. The formalism, the potentials, and the results of this paper may also serve as a basis and a realistic starting point for systematic relativistic nuclear structure studies as well as for the investigation of further relativistic many-body corrections and of contributions of higher order.
444 citations
TL;DR: In this paper, the authors use the techniques of an effective field theory for heavy quark systems to calculate lepton energy distributions in heavy meson decays, and show that there are no nonperturbative corrections of order mbΛQCD to the average invariant mass-squared of the final hadronic state.
352 citations
TL;DR: In this article, the authors reviewed the data and theory relevant to understand charge symmetry breaking in hadronic mass spittings, interactions and decay rates; nucleon-nucleon interactions; nuclear reactions; and binding energies of mirror nuclei.
334 citations
TL;DR: In this article, the authors describe the time evolution of the nuclear many-body system within a nonperturbative transport approach as well as the methods employed for the evaluation of the elementary nucleon-nucleon-particle cross sections.
330 citations
TL;DR: In this article, the mesonic (quark-antiquark) modes in a generalized Nambu-Jona-Lasinio model with three quark flavors were analyzed.
247 citations
TL;DR: In this paper, strong interaction corrections to the effective hamiltonian for weak radiative B - meson decay are calculated using the leading logarithmic approximation, where Xs denotes a strange hadronic final state.
213 citations
TL;DR: In this article, a re-evaluation of the massless three-loop next-to-leading QCD correction to the correlator of the quark scalar currents and Γtot(H0 → hadrons) is presented.
Abstract: Analytical results of a re-evaluation of the massless three-loop next-to-leading QCD correction to the correlator of the quark scalar currents and Γtot(H0 → hadrons) are presented. The states of some other QCD perturbative results is discussed.
186 citations
TL;DR: In this article, the exclusive semi-leptonic (s.l.) bottom meson decays B→D(D*)+l+v where they include non-zero lepton mass effects in the kinematics and dynamics.
Abstract: We discuss the exclusive semi-leptonic (s.l.) bottom meson decaysB→D(D*)+l+v where we include non-zero lepton mass effects in the kinematics and dynamics. We develop the general formalism for the non-zero lepton mass case. We then look at how rates, spectra and angular correlations are affected by non-zero lepton masses in the context of a specific spectator quark model. Numerical results are presented for s.l. decays involving thee-, μ- and τ-leptons. We also discuss the s.l. decaysB→π(ρ),D→K(K*) and the free quark decay model.
185 citations
TL;DR: In this article, the strangeness-changing nonleptonic weak interactions of the pseudoscalar mesons were investigated in the framework of the effective low-energy chiral lagrangian.
TL;DR: Two-pion correlation functions are calculated from a dynamical string model situation and from a Bjorken-scaling solution and the effects of hadronic decays and final-state Coulomb and strong interactions are included.
Abstract: We calculate two-pion correlation functions from a dynamical string model situation and from a Bjorken-scaling solution. The effects of hadronic decays and final-state Coulomb and strong interactions are included. Correlation functions are shown to depend strongly on both the total transverse momenta and the direction of the relative momentum of the pairs.
TL;DR: In this paper, the potentials between heavy quarks corresponding to the ground state and excited states of the gluon field are studied in pure SU(3) lattice gauge theory at β = 6.0 and β =6.2 using blocked lattice operators.
TL;DR: In this article, the correlation of vector and axial currents was investigated at low temperatures T⪡Tc, T2/6F2ππ⫡1.
TL;DR: The spectrum of baryons with two heavy quarks can be related to the spectrum of mesons with Qq flavor quantum numbers as mentioned in this paper, where the interactions of heavy color triplet objects with the light degrees of freedom (i.e. quarks and gluons) are independent of the heavy quark's spin and mass.
TL;DR: A relativistic nuclear mean field model is developed involving nucleons coupled to effective scalar and vector fields that yields a compression modulus of 225 MeV and an effective nucleon mass=0.85.
Abstract: A relativistic nuclear mean field model is developed involving nucleons coupled to effective scalar and vector fields. It differs slightly from the usual Walecka model in the form of the coupling of the nucleon to the scalar meson. We calculate the equation of state for symmetric nuclear matter at zero temperature. The model, which has no arbitrary parameters, once we fit the empirical density and energy of nuclear matter, yields a compression modulus of 225 MeV and an effective nucleon mass=0.85.
TL;DR: In this paper, a dynamical model for pseudoscalar-pseudoscalar meson scattering based on meson exchange, suitable for use in a variety of low and intermediate-energy mesonic interactions, has been constructed and applied to ππ and kπ scattering with good quantitative results.
TL;DR: In this paper, the amplitude for the exclusive non-leptonic decay of a heavy meson into two light pseudoscalar mesons is analyzed using the factorization formalism of perturbative QCD for exclusive reactions at large momentum transfer.
TL;DR: In this article, the authors present a review of quantum correlation dynamics in the non-relativistic and relativistic case and derive selfconsistent transport equations for the baryonic phase-space distribution.
TL;DR: In this article, the ARGUS detector at the DORIS II storage ring has measured B decays into exclusive final states containing aD orD* meson plus several pions, or containing aJ/ψ or ψ′ mesonplus a strange particle.
Abstract: Using the ARGUS detector at thee
+
e
− storage ring DORIS II, we have measuredB decays into exclusive final states containing aD orD
* meson plus several pions, or containing aJ/ψ or ψ′ meson plus a strange particle. Some of these channels have not been seen before, while others represent updated measurements of previous results. The branching ratios are compared with the predictions of the model of Bauer, Stech and Wirbel. Using the cleanest decay channels, the mass of the charged and neutralB meson are found to bem
B
−=(5280.5±1.0±2.0) MeV/c2 andm
B
0=(5279.6±0.7±2.0) MeV/c2 respectively, yielding a mass differencem
B
0−m
B
−
=(−0.9±1.2±0.5) MeV/c2.
TL;DR: In this paper, a meson exchange model for the K + -nucleon interaction is presented, which is constructed along the same guidelines as those applied in the Bonn model for NN interaction.
TL;DR: This work analyses semileptonic decays of mesons containing heavy quarks and indicates how to extract the signs and magnitudes of the helicity amplitudes for the exclusive decay modes involving a vector meson, lepton, and neutrino by using the joint distribution of the decay products.
Abstract: We analyze semileptonic decays of mesons containing heavy quarks and indicate how to extract the signs and magnitudes of the helicity amplitudes for the exclusive decay modes involving a vector meson, lepton, and neutrino by using the joint distribution of the decay products of the vector meson (into a pair of pseudoscalar mesons) and of the virtual {ital W} (into a charged lepton and its neutrino). We apply this to specific cases of charm- and bottom-meson decays with form factors calculated from quark models.
TL;DR: In this paper, the relativistic heavy-ion collisions were considered, and the fluxes of the Lepton pair, meson and Higgs-boson production were calculated at energies relevant for RHIC and LHC (or SSC).
TL;DR: A model calculation of some effects of virtual quark-antiquark pairs in mesons suggests that pair-creation effects can be absorbed into a renormalization of the mesonic string tension, but this masking can only be approximate, as it is shown by considering the dependence of the energy shift on the spin state of the sources.
Abstract: We present a model calculation of some effects of virtual {ital q{bar q}} pairs in mesons. Specifically, using a model for pair creation that has previously been shown to give a good description of strong meson decays, we calculate the energy shift of a static quark-antiquark pair due to the presence of virtual quark-antiquark pairs. The shift is large and approximately proportional to the distance between the static sources. The linearity of the correction suggests that pair-creation effects can be absorbed into a renormalization of the mesonic string tension. However, this masking can only be approximate, as we show by considering the dependence of the energy shift on the spin state of the sources. We conclude by pointing out the relevance of our results to the {ital N}/{rho}'' problem encountered in lattice QCD calculations.
TL;DR: In this paper, the dependence of the average transverse momentum on the charged particle rapidity density of the Centrally Produced Matter (CPM) has been investigated, and it is observed that the increase of with increasing dn/dη is more significant for heavier particles than that for lighter particles.
Abstract: In p-p collisions at √s = 1.8 TeV, the yields and the transverse momentum distributions of π±, K±, p± in the central region have been measured up to a charged particle pseudo rapidity density of (dnc/dη) ≈ 16. The dependence of the average transverse momentum on the charged particle rapidity density of the Centrally Produced Matter is presented. We observe that the increase of with increasing dn/dη is more significant for heavier particles than that for lighter particles.
TL;DR: P perturbative thermal effects overwhelm the gluon condensate contribution at a temperature around 100 MeV, so that high-temperature charmonium physics is consistent with that expected in a weakly interacting quark-gluon plasma.
Abstract: QCD sum-rule techniques are applied to the spectra of $\ensuremath{\rho}$ and $\frac{J}{\ensuremath{\psi}}$ mesons at finite temperature to investigate the relative importance of quark and gluon condensates and perturbative thermal effects in determining bound-state parameters. Of particular interest are the consequences of nonperturbative physics persisting above the deconfinement phase transition, which is implied by nonzero gluon condensates found in lattice calculations. For the $\ensuremath{\rho}$ meson, the quark thermal bath induces only a smooth variation in the hadronic parameters as the temperature is increased; the quark condensate and its temperature dependence are the most important factors. For the $\frac{J}{\ensuremath{\psi}}$ meson, perturbative thermal effects overwhelm the gluon condensate contribution at a temperature around 100 MeV, so that high-temperature charmonium physics is consistent with that expected in a weakly interacting quark-gluon plasma. Corrections to other plasma properties from nonperturbative physics are discussed.
TL;DR: In this article, the authors present a complete theoretical analysis of the decay amplitude K → π H and η → H, where H is a hypothetical light Higgs particle, based on the consistent use of the effective chiral lagrangian technique.
TL;DR: In this paper, the σ and ω mesons are motivated by the quark model and a tensor coupling of the meson to the Λ that is of equal magnitude but opposite sing to the vector coupling is shown.
TL;DR: In this article, the authors assume that quarks are described by Dirac spinors, with current masses which eventually can be set to zero, interacting through a confining and chirally invariant potential.
Abstract: In this work we assume that quarks are described by Dirac spinors, with current masses which eventually can be set to zero, interacting through a confining and chirally invariant potential. Other than the strength of the interquark potential and the current masses of the quarks we have no free parameters. {sup 3}{ital P}{sub 0} quark-antiquark vacuum condensation is allowed and the mass gap equation is solved for the chosen potential. The solution, and even the mere existence of it, depends quite sharply on the chosen potentials. Vacuum condensation is shown to be responsible for partial conservation of axial-vector current and for the constituent scale. The mass gap equation also ensures us that quark annihilation is obtained in a consistent way. In our formalism quarks and antiquarks appear explicitly, which greatly simplifies the derivation of both the Salpeter equations for meson bound states and the resonating-group-method equations for meson decays and scattering.
TL;DR: The tensor coupling of the ϱ meson to the nucleon, in analogy to the isovector transverse form factor for electron scattering from nuclei, is enhanced by replacing the mass mn, which occurs in the denominator of each of these, should be replaced in medium by the effective nucleon mass m n ∗. This leads to an increase in ϱ-exchange interaction in medium as mentioned in this paper.