Showing papers on "Pseudoscalar published in 1987"
TL;DR: In conjunction with measurements of the electron’s anomalous magnetic moment, this experiment shows that the narrow positron peaks observed in heavy-ion collisions at the Gessellschaft fur Schwerionenforschung are not due to an elementary pseudoscalar.
Abstract: We report results of an electron-beam-dump search for neutral particles with masses in the range 1 to 15 MeV and lifetimes τ between 10^-14 and 10^-10 s. No evidence was found for such an object. We fule out the existence of any 1.8-MeV pseudoscalar boson with τ>8.2×10^-15 s and an absorption cross section in matter less than 1 mb per nucleon, and exclude τ>1×10^-14 s were its cross section to equal 50 mb per nucleon. In conjunction with measurements of the electron’s anomalous magnetic moment, this experiment shows that the narrow positron peaks observed in heavy-ion collisions at the Gessellschaft fur Schwerionenforschung are not due to an elementary pseudoscalar.
418 citations
TL;DR: A laboratory experiment to produce and detect a light neutral pseudoscalar particle that couples to two photons that compete favorably with astrophysical limits and would substantially improve those from direct measurements.
Abstract: We propose a laboratory experiment to produce and detect a light neutral pseudoscalar particle that couples to two photons. The pseudoscalar would be produced by a (real) photon from a laser beam interacting with a second (virtual) photon from a static magnetic field; it would be detected after it reconverts to a real photon in a duplicate magnetic field. The bounds on the coupling constant that could be obtained from a null result in such an experiment compete favorably with astrophysical limits and would substantially improve those from direct measurements.
239 citations
CERN1
TL;DR: In this paper, the decay constant of the pseudoscalar B-meson was shown to be (1.38 ± 0.14) ǫ −π for relativistic Laplace (Borel) sum rules.
119 citations
TL;DR: A lattice derivation of the Witten-Veneziano mass formula for the neutral pseudoscalar bosons is given in this article, where a lattice construction is given for the mass formula.
42 citations
TL;DR: In this paper, a perturbative QCD analysis is presented for the inclusion of pseudoscalar and vector mesons to derive the fragmentation function of heavy quarks produced in e + e − annihilation.
35 citations
TL;DR: In this paper, the vector dominance model is reexamined in a semi-empirical approach and the vector-meson mixing angle and a single vector-vector-pseudoscalar coupling constant for an effective VVP lagrangian is calculated from the V → πλ decay widths.
29 citations
TL;DR: In this paper, the free nucleon is treated as a relativistic three-quark system in light-front formalism, and Coupled integral equations are derived for the three invariant momentum distributions of the nucleon for two quark interactions with scalar, vector, and pseudoscalar vertices.
25 citations
TL;DR: In this paper, the 8.6 million J/ψ collected by the DM2 detector at DCI have been analysed looking for the Jψ→γωω decay, both ω's decaying into π+π−π0.
25 citations
TL;DR: In this article, two alternative formulations of the meson exchange currents and of the associated response to an electromagnetic field are derived in the path integral framework for a system of nucleons and pions with either a pseudoscalar or a pseudovector interaction.
22 citations
TL;DR: In this paper, the Higgs scalar h and the pseudoscalar A are discussed, as well as ways to distinguish between decays involving both the scalar and A.
10 citations
TL;DR: In this article, the production of pseudoscalar glueballs in J/ψ radiative decays was investigated and the results favour the interpretation of ι (1460) as a fairly pure glueball state.
TL;DR: In this article, an effective Lagrangian for massive pseudoscalar mesons is obtained from the generating functional of quantum chromodynamics by the method of chiral bosonization, and it is shown that the low energy region in the integral over the quark fields is characterized by quark and gluon condensates.
Abstract: An effective Lagrangian for massive pseudoscalar mesons is obtained from the generating functional of quantum chromodynamics by the method of chiral bosonization. It is shown that the low-energy region in the integral over the quark fields is characterized by quark and gluon condensates. Expressions are found for the chiral anomaly and the anomalous action in external vector, pseudovector, scalar, and pseudoscalar fields, allowance being made for the asymmetry of the quark spectrum.
TL;DR: In this paper, a model for explaining the decay of charmed mesons is applied to study their explicit decay into two pseudoscalar mesons, which leads in a natural way to the enhancement of the hitherto neglected W-exchange and W-annihilation decay modes.
TL;DR: The original vacuum-insertion calculation of the penguin-induced K/sup 0/-2..pi.. amplitude by Shifman, Vainshtein, and Zakharov (SVZ) gives the correct chiral result even though only the momentum dependence in is taken into consideration in the SVZ work.
Abstract: The momentum dependence of the matrix elements of quark bilinear scalar and pseudoscalar densities is determined from chiral perturbation theory. We explain why the original vacuum-insertion calculation of the penguin-induced K/sup 0/-2..pi.. amplitude by Shifman, Vainshtein, and Zakharov (SVZ) gives the correct chiral result even though only the momentum dependence in is taken into consideration in the SVZ work.
TL;DR: In this article, the pseudoscalar masses and decay constants in QCD with three flavors were calculated using a previously proposed form for the effective potential and taking into account renormalization group corrections.
TL;DR: In this paper, a relativistic model was used to predict cross sections for the nuclear (e, e'K + ) reaction, where the transition operator is derived from Feynman diagrams and the nuclear and hypernuclear wave functions contain Dirac-Hartree orbitals obtained from a relatival nuclear structure model extended to hypernuclei.
TL;DR: This paper deals with a determination of both the masses and the widths of vector mesons using QCD sum rules, which has been used to determine the resonance parameters of the rho, K/sup, and phi mesons.
Abstract: This paper deals with a determination of both the masses and the widths of vector mesons using QCD sum rules. The lowest-lying contribution to the dispersion integral arising from the state of two pseudoscalar mesons is written in terms of the meson form factor. The form factor is expressed in a Breit-Wigner or a related form, which involves the mass and the width of the vector-meson resonance. Using this technique, the QCD sum rule has been used to determine the resonance parameters of the rho, K/sup */, and phi mesons.
TL;DR: In this paper, a nonrelativistic potential model was proposed to predict the spectrum of heavy and light mesons and the leptonic-decay width of vector mesons.
Abstract: Using a new nonrelativistic potential model we predict the spectrum of heavy and light mesons and the leptonic-decay width of vector mesons. The potential contains a regularized Coulomb part which allows a nonperturbative treatment of the spin-dependent interaction. In addition, we calculate the electromagnetic mass differences of pseudoscalar and vector mesons. The influence of themd-mu mass difference on the strong interaction can be larger than the electromagnetic effect itself. The mass dependence of this effect is discussed in some detail.
TL;DR: The reaction /sup 1/H(..gamma..,K/sup +/)..lambda../sup 0/ is used to compare pseudovector with pseudoscalar coupling for the K..lambda..N vertex and obtains the coupling constants from a least squares fit.
Abstract: The reaction /sup 1/H(..gamma..,K/sup +/)..lambda../sup 0/ is used to compare pseudovector with pseudoscalar coupling for the K..lambda..N vertex. The operator is based on diagrammatic techniques and includes the Born terms along with the K/sup */ and ..sigma.. exchange terms. Obtaining the coupling constants from a least squares fit shows that the data do not prefer one coupling over the other. Implanting the process into the nucleus yields only small differences between the two interactions.
TL;DR: In this paper, the Gell-Mann-Oakes-Renner type approach to the chiral U(3) x U (3) and also U(4) × U( 4) algebras involving anomaly was used to study the TJ-TJ-l mixing.
Abstract: We have studied the TJ-r/-l mixing by using the Gell-Mann-Oakes-Renner type approach to the chiral U(3) x U(3) and also U(4) x U(4) algebras involving anomaly and found that TJ'-l mixing could be appreciable. The model also predicted (by using PCAC and also sometimes a simple quark counting argument) that while the rate of I ~ rr is relatively small, r(l ~ prj will be rather large""l MeV. The TJ-TJ'-l mixing has also been studied by us using the method of "asymptotic flavor SU(3) symmetry plus the constraint algebras involving the generators of underlying symmetry groups of QCD". Essentially the same conclusion as derived in the first approach has been obtained for the structures of TJ-TJ'-l mixing. In this paper, we study the l~rr and l~pr decays in the second approach without using quark counting argument. We find a result which is compatible (at least in flavor SU(3) symmetry studied) with that of the first approach. We conclude that a part of the present experimental situation can be understood with the presence of pseudoscalar glueball 1(1440) which mixes rather appreciably with the TJ'. Critical experiments for the model are also discussed.
TL;DR: In this paper, a comparison of differential distributions and total widths for scalar and pseudoscalar boson production in η -quarkonium decays is carried out.
01 Apr 1987
TL;DR: An effective Lagrangian of two-dimensional scalar electrodynamics that takes into account the effects of the complicated vacuum structure in the model is found in this paper, which is used to calculate the Green's functions for the gauge-invariant operators that interpolate the scalar and pseudoscalar fields.
Abstract: An effective Lagrangian of two-dimensional scalar electrodynamics that takes into account the effects of the complicated vacuum structure in the model is found. The effective Lagrangian is used to calculate the Green's functions for the gauge-invariant operators that interpolate the scalar and pseudoscalar fields.
01 Jan 1987
TL;DR: In this paper, the PNC neutral weak coupling is decribed by an effective zero-range pseudoscalar potential Hp = H1 + H2 that must be added to the usual atomic Hamiltonian.
Abstract: Parity nonconservation (PNC) in an atom arises from interference between the neutral weak and electromagnetic interactions that couple a valence electron to the nucleus. The PNC neutral weak coupling is decribed by an effective zero-range pseudoscalar potential Hp = H1 + H2 that must be added to the usual atomic Hamiltonian. The dominant portion H1 involves the axial and vector parts of the electronic and nucleonic neutral weak currents, respectively. H1 is proportional to Fermi’s constant GF and to the “weak charge” QW. (In the standard model, QW = Z(1-4sin2θw)-N before radiative corrections, and Z=proton number, N=neutron number, while θw is Weinberg’s angle). H1 connects only s1/2, and P1/2 orbitals, and its matrix elements vary roughly as Z2Qw. H2 arises from the coupling of vector electronic and axial hadronic weak currents, and its matrix elements are several orders of magnitude smaller than those of H1. All experiments completed so far have been sensitive only to H1; they may be regarded as measurements of Q, and thus of sin2θw.
01 Jan 1987
TL;DR: A lattice derivation for the neutral pseudoscalar masses in lattice QCD leads to a formula for the topological susceptibility through the fermion fields, in which the gauge field topological charge is recovered via the Atiyah-Singer index theorem as mentioned in this paper.
Abstract: A lattice derivation for the neutral pseudoscalar masses in lattice QCD leads to a formula for the topological susceptibility through the fermion fields, in which the gauge field topological charge is recovered via the Atiyah-Singer index theorem. A numerical study in two dimensional QED gives insight into corrections due to a non-zero lattice distance.
TL;DR: In this article, a constituent model for pseudoscalar mesons containing quarks and gluons is presented, and the results indicate that the mesons may be understood as a mixture of a q q -state and an hermaphrodite, i.e. a state q q g.
TL;DR: In this article, the authors investigated the QCD sum rules of Shifman, Vainstein and Zakharov from the point of view of analytical extrapolations: in the weighted sum rule the analyticity connects the low energy hadron parameters with the high energy QCD parameters (coupling constant, quark masses, condensate parameters).
Abstract: QCD sum rules of Shifman, Vainstein and Zakharov are investigated from the point of view of analytical extrapolations: in the weighted sum rule the analyticity connects the low energy hadron parameters with the high energy QCD parameters (coupling constant, quark masses, condensate parameters). It is shown that the optimal weight function in the sum rule is prescribed by the errors of the input information. The optimal tests of analyticity are proposed and applied (under some simplifying assumptions) to the vector and pseudoscalar charmonium channels.
TL;DR: In the minimal supersymmetric extension of the standard model one scalar Higgs boson is forced to be lighter than the Z 0 as mentioned in this paper, and it turns out that, although fairly stringent limits are found, it is still conceivable that this particle is light enough to be discovered at SLC and LEP.
TL;DR: The sign and magnitude of the amplitude β for isoscalar quark annihilation into two gluons followed by their creation into an isosalar meson dominates particle nonet mixing as mentioned in this paper.
Abstract: The sign and magnitude of the amplitude β for isoscalar\(\bar qq\) quark annihilation into two gluons followed by\(\bar qq\) creation into an isoscalar meson dominates particle nonet mixing. The consequent theory of particle mixing and also its phenomenology uniformly predict that the pseudoscalar and vector isoscalar amplitudes βp and βV are positive in sign. We present simple arguments to show that the positive sign of βp may readily result by any mechanism such as gluon confinement and/or asymptotic freedom which will suppress contributions from high-energy gluon intermediate states. This also explains why the corresponding βpp parameter for the parapositronium state in QED is negative in contrast.