Showing papers on "Pseudoscalar published in 1986"
TL;DR: In this article, an effective low-energy lagrangian of composite scalar, pseudoscalar, vector and axial-vector mesons was derived by bosonization of an extended Nambu-Jona-Lasinio type of quark model with explicit breaking of chiral U (n) × U(n) symmetry.
392 citations
TL;DR: In this article, a quenched, planar approximation of the quantum electrodynamics is studied in four dimensions and the pseudoscalar Goldstone boson is observed.
201 citations
TL;DR: In this article, the αS correction to heavy quarkonium decay into scalar and pseudoscalar plus gamma was presented, which brings about a substantial reduction in the rate.
66 citations
TL;DR: Axion photoproduction is suggested as a systematic technique for investigating the coupling of new elementary pseudoscalar or scalar particles in the megaelectronvolt mass range to leptons, photons, and hadronic matter.
Abstract: Axion photoproduction is suggested as a systematic technique for investigating the coupling of new elementary pseudoscalar or scalar particles in the megaelectronvolt mass range to leptons, photons, and hadronic matter. The experiments involve a configuration where a low-energy photon collides with a relativistic electron beam. Threshold production energies of 300 GeV can be accomplished with an optical laser, and those of 14.5-50 GeV can be achieved with wigglers directed onto an electron beam. With this scheme, at least 10 to the -7th of the electrons can be converted to axions, providing a 1-100 thousand/s relativistic beam of axions.
25 citations
TL;DR: The chiral SU( 2)/sub L/ x SU(2)/sub R/ cloudy bag model is used to calculate magnetic dipole radiative transitions among pseudoscalar and vector mesons and a new picture for these decays emerges.
Abstract: We use the chiral SU(2)/sub L/ x SU(2)/sub R/ cloudy bag model to calculate magnetic dipole radiative transitions among pseudoscalar and vector mesons. A new picture for these decays emerges. Three different dynamical mechanisms, photon emission by quarks, photon emission from the pion cloud, and pion emission by mesonic bags accompanied by a transition from a vector bag to a photon, contribute singly or in combination to the 11 possible M1 transitions. The model accounts well for the observed rates. In particular, pion-cloud effects are necessary to explain the K( decays.
23 citations
TL;DR: In this article, the influence of internal nucleon structure on meson exchange currents has been investigated, in the framework of the nonrelativistic constituent quark model and the MIT bag model with massless quarks.
Abstract: The influence of internal nucleon structure on meson exchange currents has been investigated, in the framework of the nonrelativistic constituent quark model and the MIT bag model with massless quarks. In comparison with the conventional theory of exchange currents, one finds different strengths for the model-dependent higher-order terms and no ambiguity between pseudoscalar and pseudovector pion couplings. Furthermore, the retardation and excitation effects in the many-body system have to be treated consistently, in order to preserve gauge invariance. In this way one obtains 'damping' factors, which differ in structure from the phenomenological form factors.
22 citations
TL;DR: Effective Lagrangians for these reactions are also constructed using superfields, thus confirming that these widths of scalar and pseudoscalar decay widths do not vanish in the supersymmetric limit.
Abstract: We calculate the one-loop contribution to the two-photon decay widths of scalar and pseudoscalar bosons in a supersymmetric SU(2)\ifmmode\times\else\texttimes\fi{}U(1) gauge theory using component fields. Effective Lagrangians for these reactions are also constructed using superfields, thus confirming that these widths do not vanish in the supersymmetric limit.
20 citations
TL;DR: In this paper, the long-range parts of the potentials arising from simple color-singlet qq exchanges have been evaluated in explicit analytic form, and it is shown that these arise almost entirely through two of the 25 possible types of exchange terms, and that these two correspond to the simple exchange of a qq pair between the two nucleons.
18 citations
TL;DR: The two-photon decay widths of nonstandard Higgs bosons are studied in a minimal broken-supersymmetry model and a severe upper bound on this possible enhancement is imposed by the supersymmetry features of the model.
Abstract: The two-photon decay widths of nonstandard Higgs bosons are studied in a minimal broken-supersymmetry model. For two-Higgs-doublet models in general, a large enhancement of these widths relative to the standard model is possible. However, we find for the case studied that a severe upper bound on this possible enhancement is imposed by the supersymmetry features of the model. With only the t-italic quark as the heaviest fermion we find a two-photon width of 100 keV for a 160-GeV/c-italic/sup 2/ scalar Higgs boson is possible. The corresponding width for a pseudoscalar is 60 keV.
17 citations
TL;DR: In this article, it was shown that if the condensate | 〈 Q Q〉 | = F 3 defines a scale F⪢ΛQCD, as has been expected on the basis of perturbative and lattice calculations, then present limits on axions exclude a wide range of values of F.
13 citations
CERN1
TL;DR: In this paper, the nature of the singlet pseudoscalar and scalar particles in the four-dimensional low energy effective theory derived from the superstring is clarified, and the absence of any new physics in the Wess-Zumino terms of the ten-dimensional anomaly-free supergravity theory is emphasized.
TL;DR: In this article, a summary on radiative decays of the ψ states is presented, with a detailed understanding of the excited pseudoscalar nonscalar nonet.
TL;DR: The coupling to u-italic and d-ITALic quarks of a possible new light pseudoscalar particle observed in heavy-ion collisions is estimated to be of the order 10/sup -3/ from rare ..pi.. and K-italics decays.
Abstract: The coupling to u-italic and d-italic quarks of a possible new light pseudoscalar particle observed in heavy-ion collisions is estimated to be of the order 10/sup -3/ from rare ..pi.. and K-italic decays.
TL;DR: Pion decay amplitudes of nonstrange baryon resonances are calculated assuming a pseudoscalar single-quark-emission-type model for the decay process and the decay widths are compared to the available experimental data and to other theoretical results.
Abstract: Pion decay amplitudes of nonstrange baryon resonances are calculated assuming a pseudoscalar single-quark-emission-type model for the decay process. The resonances as well as the nucleon ground state are described by configuration mixings obtained previously in a semirelativistic QCD-inspired quark model. The decay widths are compared to the available experimental data and to other theoretical results.
TL;DR: In this article, it was shown that there are two pseudoscalar states nearly degenerate and possibly overlapping in the mass region of radially excited nonscalar nonets, and very different mass spectra and Dalitz plots were observed in this mass region for radiative ψ decay, vector-pseudoscalar ψ decays, pion-induced reactions, kaoninduced reactions with vector exchange and tensor exchange.
TL;DR: The decay of /sup 3/S/sub 1/(QQ)..-->..H/sup +/H/Sup -/ for a hypothetical fourth-generation quarkonium and find that it can dominate the decay rate.
Abstract: Some effects of the charged and neutral Higgs scalars in two-doublet theories on the decays of heavy quarkonia are discussed. Large changes in the rate for /sup 3/S/sub 1/(tt-bar)..-->..bb-bar via charged-Higgs-boson exchange are possible as are decays of /sup 1/S/sub 0/(QQ) states into pairs of scalar/pseudoscalar Higgs particles. We also discuss the decay /sup 3/S/sub 1/(QQ)..-->..H/sup +/H/sup -/ for a hypothetical fourth-generation quarkonium and find that it can dominate the decay rate.
TL;DR: In this paper, the appearance of the pseudoscalar isovector Goldstone mode is studied, which is generated by spontaneous breakdown of chiral symmetry due to the selfconsistent confining potential.
TL;DR: The phase structure of the fermionic system in the non-Abelian sigma model is studied and a (finite or infinite) discontinuity is found in the specific heat at the critical temperature at which symmetry is restored.
Abstract: The phase structure of the fermionic system in the non-Abelian sigma model is studied. A (finite or infinite) discontinuity is found in the specific heat at the critical temperature at which symmetry is restored. The effect of introducing quantum fluctuations (leading to temperature-dependent scalar and pseudoscalar masses) on the specific heat is also studied.
TL;DR: In this article, a selfconsistent second order gluon annihilation diagram calculation for the U(1) singlet η0 mass based on a once-subtracted dispersion relation is presented.
Abstract: We present a self-consistent second order gluon annihilation diagram calculation for the U(1) singlet η0 mass based on a once-subtracted dispersion relation. A value in the same range as the one obtained by particle mixing considerations is obtained.
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TL;DR: In this paper, the authors considered the possibility that the E(1420) originally seen in PP annihilation at rest and originally believed to be a JPC=1++ state is actually a pseudoscalar state distinct from the ι(1460) seen in radiative ψ decay.
TL;DR: In this article, the decay width of the lowest pseudoscalar glueball is calculated as a function of its mass, using an effective interaction for the glueball field with the gluons, and assuming that this glueball state is so narrow that a perturbative treatment makes sense.
TL;DR: In this paper, the influence of the pseudoscalar on the Higgs spectrum was derived in terms of two Higgs doublets in the one-loop approximation for SU2⊗U1, charged and neutral Higgs-boson masses.
Abstract: Calculating the effective potentialVeff(φ1,φ2), in terms of two Higgs doublets in the one-loop approximation forSU2⊗U1, charged and neutral Higgs-boson masses can be derived explicitly. In the presence of an invisible axion with an extra Higgs singletF, the influence of the pseudoscalar on the Higgs spectrum can be obtained withVeff(φ1,φ2;F) respectively simply via the tadpole method usingVeff(〈φ1,2〉0=υ1, 2; 〈F〉0=υ0) only.
01 May 1986
TL;DR: In this article, a phenomenological Lagrangian for the strong and electromagnetic interactions of mesons at low energies on the basis of a model with a four-quark interaction of superconducting type is reviewed.
Abstract: Studies devoted to the construction of phenomenological Lagrangians for the strong and electromagnetic interactions of mesons at low energies on the basis of a model with a four-quark interaction of superconducting type are reviewed. The scalar, pseudoscalar, vector, and two axial-vector meson nonets are considered. It is shown that because of spontaneous breaking of chiral symmetry the light current quarks become heavier constituent quarks. The strong and radiative decays of the five meson nonets, the ..pi pi.. and ..pi..K scattering lengths, and the electromagnetic radii and polarizabilities of the pions and kaons are described.
TL;DR: Gluon admixtures in neutral pseudoscalar mesons are considered to test the quark-line rule for the reactions pi p to eta Delta, eta n, pp to pi pi eta, etc as mentioned in this paper.
Abstract: Gluon admixtures in neutral pseudoscalar mesons are considered to test the quark-line rule for the reactions pi p to eta Delta , eta n, pp to pi pi eta , etc. It is found that the experimental data on these reactions support the possibility of a small gluonium admixture in the eta and eta ' states. The results have also been used to predict some electromagnetic decay rates of the pseudoscalar glueball states l(1440) along with those of eta and eta '.
TL;DR: In this paper, the generalized phenomenological chiral lagrangian method, including spin-1 mesons, pseudoscalar mesons and baryons, was proposed for describing the partial width ratios for nonleptonic weak decays of a charmed baryon.
TL;DR: In this article, the decay widths for ρ − → π − π 0 and ρ− → γ − γ are determined in a relativistic calculation where the ρ-meson is taken as a quark-antiquark bound state but the pion is treated as an elementary particle, coupling directly to the quarks.
TL;DR: In this article, the decays of 3S1 quarkonia into a photon and a scalar or pseudoscalar Higgs particle are examined, taking into account the bound-state dynamics in the framework of a nonrelativistic potential model.
Abstract: The decays of3S1 quarkonia into a photon and a scalar or pseudoscalar Higgs particle are examined, taking into account the bound-state dynamics in the framework of a nonrelativistic potential model. We find that for realistic quark potentials the naive calculation [1] overestimates the scalar rate. Numerical results are obtained for the\(\bar bb\) and\(\bar tt\) quark systems.
TL;DR: In this paper, the amplitudes among pseudoscalar mesons including possible real or virtual weak and EM bosons are derived by expanding the effective action of the composite operator formalism.
TL;DR: In this paper, the axial model in a background gravitational field was studied and the anomalous divergence of the current and the exact generating functional of the theory was obtained using the ζ-function regularization.
Abstract: We study the axial model in a background gravitational field. Using the ζ-function regularization, we obtain explicity the anomalous divergence of the axial-vector current and the exact generating functional of the theory. We show that, as a consequence of a space-time-dependent metric, all differential equations involved in the theory generalize to their covariantized forms. We also comment on the finitemass renormalization exhibited by the pseudoscalar field and the form of the fermion propagator.