Showing papers on "Pseudoscalar published in 1980"
TL;DR: In this paper, an effective lagrangian describing the low-energy spectrum and dynamics of the pseudoscalar nonet in the large N-colour limit of QCD was constructed.
564 citations
TL;DR: In this article, the results of perturbative QCD calculations are reformulated as renormalization-scheme independent predictions; in so doing, they obtain a renormalisation group improvement of the perturbation theory.
350 citations
TL;DR: In this article, a scalar meson coupled strongly to gluons is discussed, and the authors use QCD sum rules to find both Γ(J/ψ→σγ) in terms of 〈0|αsGμνaGμπaGπνa|σ〉, where σ is the presumed scalar gluonium.
171 citations
TL;DR: In this article, an effective Lagrangian with scalar and pseudoscalar ''matter'' fields and color-singlet gluon fields is constructed, which is a representation of quantum chromodynamics in that it has the same symmetry structure as that theory.
Abstract: An effective Lagrangian with scalar and pseudoscalar ''matter'' fields as well as scalar and pseudoscalar (gauge-invariant) color-singlet gluon fields is constructed. It is a representation of quantum chromodynamics in that it has the same symmetry structure as that theory. The present model is a generalization of a one- (pseudoscalar) gluon-field effective Lagrangian which compactly summarizes the results of the 1/N/sub c/ approximation, gives a simple picture for the ''U(1) problem,'' and essentially reduces to a type of generalized sigma model. The new feature here is that, in addition to the chiral-anomaly equation, the trace-anomaly equation is automatically fulfilled. This gives a framework for discussion of the properties of a 0/sup +/ color-singlet gluon field. The model may be formulated either so that this field is eliminated by a constraint equation or so that it is associated with a physical particle. Probably, experiment is the best way at present of deciding between the two possibilities. A number of possibilities for further generalization of the effective Lagrangian, including a hint of a possible connection with the ''confinement'' problem, are mentioned.
157 citations
TL;DR: Hadronic coupling constants of the vertices including charmonium mesons are calculated in a nonrelativistic quark model as discussed by the authors, which takes into account the SU4 breakings through different masses of quarks and different wave functions in the overlap integrals.
67 citations
TL;DR: In this article, it was shown that one can interpret the experimental data on the δ-meson in favour of the four-quark model (qqqq), i.e. explain the data supposing the Zweig super-allowed coupling of the scalar δmeson with pseudoscalar ones and using the relations predicted in the q-qq-model for the coupling constants of the π η, KK and πη′-channels.
52 citations
TL;DR: In this article, the perturbative and non-perturbative contributions to the vacuum polarization from the pseudoscalar current in the unequal mass case were computed to first order in α s.
45 citations
CERN1
TL;DR: In this paper, the effect of the pseudoscalar coupling constant g P on the one-body hamiltonian was investigated in the photon energy domain of interest, with minor corrections due to the muon propagator in the nuclear field and the two-step process.
21 citations
TL;DR: In this article, a relativistic wave equation is derived for gauge-invariant J=0 gluonium amplitudes, and its reduced eigenvalue equation is identical with that for a quark-antiquark system in /sup 3/P/sub 1/ states.
Abstract: A relativistic wave equation is derived for gauge-invariant J=0 gluonium amplitudes, and show that its reduced eigenvalue equation is identical with that for a quark-antiquark system in /sup 3/P/sub 1/ states. Analysing relations between potentials in the two respective systems, I obtain an upper limit of 2 GeV to the ground-state mass if I take light quarkonium as a reference system, whereas I estimate the ground state to lie between 2.5 and 3 GeV if I use charmonium potential parameters. The scalar and the pseudoscalar gluonium states are degenerate in the present approach.
16 citations
TL;DR: In this article, the authors estimate hadronic self-energy effects to pseudoscalar (P) and vector (V) meson states due to the P→PV→P, P→VV/P, V→ PPV/V, PV→V, VV/PPV, PPV→PPV and VVV vertices, and they use a common cut-off ofkcm≃ 0.7 GeV/c corresponding to a harmonic oscillator radius of ≃0.7 fm.
Abstract: We estimate hadronic self-energy effects to “bare” pseudoscalar (P) and vector (V) meson states due to theP→PV→P, P→VV→P, V→ PP→V, V→PV→V andV→VV→V loops. We simulate higher order diagrams by consistently requiring external and internal particles to have the same mass. We find good agreement with all the experimental masses (exceptmπ), widths and mixing angles. The “bare”P andV states are heavy (≈1.26 GeV) and degenerate up to a smallms−mu quark mass difference term. The “bare” coupling constants for thePPV, PVV andVVV vertices obey exact OZI rule and almost exact SU(6)W symmetry. We use a common cut-off ofkcm≃0.7 GeV/c corresponding to a harmonic oscillator radius of ≃0.7 fm for all SU(6)W related thresholds except for the pion.
11 citations
TL;DR: In this article, it was shown that a successful description of pseudoscalar mixing requires a pseudoscalar ghost glueball field, which is not the case in this paper.
Abstract: We comment on some work of Rosenzweig, Schecter, and Trahern who construct an effective Lagrangian for quantum chromodynamics involving a pseudoscalar ghost glueball field. We point out that a successful description of pseudoscalar mixing we wrote down some years ago indeed requires a pseudoscalar ghost.
TL;DR: In this paper, the photoproduction of charmed particles by polarized photons is calculated in perturbative quantum chromodynamics, and the resulting linearly polarized photon asymmetry is found to be large and negative, therefore providing a distinctive test of the proposed production mechanism.
Abstract: The photoproduction of charmed particles by polarized photons is calculated in perturbative quantum chromodynamics. For vector gluons the resulting linearly polarized photon asymmetry is found to be large and negative, therefore providing a distinctive test of the proposed production mechanism. Predictions are also given for scalar and pseudoscalar gluons and the magnitude of the cross section is discussed.
01 Jan 1980
TL;DR: In this article, the upsilon spectrum is discussed as well as the effects of radial and pseudoscalar mixing in a charmonium model with relativistic corrections which reproduces the s-wave spectrum, the leptonic widths, and the p-wave splittings.
Abstract: We take the recently found charmonium state at 2.976 GeV to be the ηc and show that it can be included in a charmonium model with relativistic corrections which reproduces the s-wave spectrum, the leptonic widths Γ(V→e+ e−) and the p-wave splittings. The upsilon spectrum is discussed as are the effects of radial and pseudoscalar mixing.
TL;DR: In this paper, the quark couplings in flavor-changing semileptonic transitions induced by lowest-order gluon corrections are computed and the effect of these radiative corrections on the axial-vector coupling is investigated.
Abstract: We compute the quark couplings in flavor-changing semileptonic transitions induced by lowest-order gluon corrections. We investigate the consequences of these radiative corrections for the quark axial-vector coupling, the deviations from Cabibbo universality for the axial-vector relative to the vector current, and the induced couplings (first-class pseudoscalar and anomalous magnetic moment, and second-class scalar and pseudotensor). The correction lowers the axial-vector coupling and increases the magnetic moment. We study the dependence of the couplings on the quark mass difference. Some of these results, true to all orders in ..cap alpha../sub s/, generalize the theorem of Ademollo and Gatto. The effective current is pure V-A to a very good approximation for transitions of heavy quarks (m> or approx. =5 GeV).
CERN1
TL;DR: In this article, the authors study the 14 (γ, π + ) 14 Cg g. The vanishingly small Gamow-Teller matrix element allows them to probe corrections to the normally dominant σ · e (Kroll-Ruderman) term.
TL;DR: In this paper, various non-relativistic pion production operators are applied in the study of the 4 He(p, nπ + ) 4 He process and compared with fully covariant calculations of the external emission graphs both for pseudovector and pseudoscalar coupling.
TL;DR: In this article, the evolution of masses with a scaleM is investigated in scalar and pseudoscalar gluon theories for the comparison with QCD, and the scalar theory shows the increase of effective masses withM, and therefore it cannot be a candidate for the theory of strong interactions.
Abstract: The evolution of masses with a scaleM is investigated in scalar and pseudoscalar gluon theories for the comparison with QCD. The scalar theory shows the increase of effective masses withM, and, therefore, it cannot be a candidate for the theory of strong interactions. In pseudoscalar gluon theory effective masses become lighter at higherM, just like in QCD.
TL;DR: In this article, a simple model for non-diffractive axial vector meson production at intermediate energies is presented, where data on analogous pseudoscalar production processes are used to predict the production properties of the A1(JPC=1++) and B(1+-) SU(3) nonets.
Abstract: Presents a simple model for non-diffractive axial vector meson production at intermediate energies. Data on the analogous pseudoscalar production processes are used to predict the production properties of the A1(JPC=1++) and B(1+-) SU(3) nonets. A unitary, coupled-channel formalism then allows one to predict the s, t and m2 dependence of the Q-like enhancements which are observed in the K rho and K* pi channels produced in charge and hypercharge exchange processes. Detailed predictions for forthcoming experiments are made. Existing data are in qualitative agreement with the model.
TL;DR: In this paper, the K/sub l/3 form factors were investigated in the one-loop approximation within the context of a linear renormalizable SU(3) sigma model, and the results showed that the second-order corrections were usually in the neighborhood of 15--20% or less, supporting the conjecture that higher-order strong-interaction effects may, in most cases, be rather small.
Abstract: The K/sub l/3 form factors are investigated in the one-loop approximation within the context of a linear renormalizable SU(3) sigma model. The model incorporates SU(3) nonets of pseudoscalar (..pi..,K,eta,eta') and scalar (epsilon,kappa,sigma,sigma') mesons. The eta', epsilon, kappa, sigma, and sigma' mesons are associated with the X/sup 0/(957), delta (980), kappa (1400), S* (980), and epsilon (1300), respectively. The Lagrangian contains the most general renormalizable chiral-SU(3) x SU(3) -invariant couplings as well as explicit linear symmetry-breaking terms belonging to the (3,3*) direct-sum (3*,3) representation of SU(3) x SU(3). All calculations are carried out in the one-loop approximation. With this model we first obtain a reasonable approximation to the scalar and pseudoscalar mass spectrum and the known leptonic decay constants. Most of the masses and decay constants are reproduced within 10%. In addition, the second-order corrections were usually in the neighborhood of 15--20% or less, supporting the conjecture that higher-order strong-interaction effects may, in most cases, be rather small. Employing these solutions, we calculate the K/sub l/3 form factors and compare these with recent experimental studies. The predictions for lambda/sub +/ are too small probably due to the fact that, at this level of approximation, the model contains no spin-one poles (vectormore » mesons). However, the model predictions for lambda/sub 0/ and xi (0) are fairly good. A number of theoretical predictions for the K/sub l/3 form factors based on current algebra and chiral perturbation theory are then investigated. In particular, we were interested in the magnitude of the corrections to various predictions derived using specific symmetry assumptions.« less
TL;DR: In this paper, a parity-violating potential for the Weinberg-Salam model is calculated for the separable approximation using empirical form factors to describe matrix elements of weak currents.
Abstract: A nucleon-nucleon parity-violating potential is calculated for the Weinberg-Salam model in the separable approximation using empirical form factors to describe matrix elements of weak currents. The connection between the separable approximation and the dispersion-theoretical calculation of the Born pole term is also considered. The separable contribution to the nucleon-nucleon-pion parity-violating amplitude is connected with the induced pseudoscalar contribution in parity-violating nucleon-nucleon scattering.
TL;DR: In this paper, the nonlocal interaction of a spinor and a pseudoscalar field is considered in the framework of gradient coupling, and a relativistically invariant form factor in the neutrino propagator is achieved.
Abstract: The nonlocal interaction of a spinor and a pseudoscalar field is considered in the framework of gradient coupling. By the introduction of a relativistically invariant form factor in the neutrino propagator, renormalizability of the theory is achieved. It is shown that the number of primitive diagrams is just four, one of which is the neutrino self-energy diagram. The Pauli-Villars regularization procedure is carried out for this diagram.
TL;DR: In this article, vector meson production in the hypercharge exchange reactions was studied at 7 GeV/c and 11.5 GeV /c using the SLAC Hybrid Facility, and the total and differential cross sections, hyperon polarization, and Vector meson decay angular distributions were presented.
TL;DR: In this article, it was shown that mesons behave during a fraction of their life like systems of two quark-antiquark pairs, and that the extra quarkantiquarks pair results from the materialization of a gluon emitted by one of the valence constituents, and derived some general properties of this four-body wave function.
Abstract: Mesons behave during a fraction of their life like systems of two quark-antiquark pairs. We assume that the extra quark-antiquark pair results from the materialization of a gluon emitted by one of the valence constituents, and we derive some general properties of this four-body wave function. The wave function seems to be made of two components, of which one is the source of most meson decays. The two components are explicited in the case of pseudoscalar and vector mesons. It is found that much information about the mechanism of disintegration can be learned from the decays of heavy but low-spin mesons like the ρ′ and the ηc.