Showing papers on "Pseudoscalar published in 1996"
TL;DR: In this paper, the pseudoscalar exchange interaction splits the multiplets of SU (3) F × SU (2) S × U (6) conf in the spectrum, and the position of these multiplets differs in the baryon sectors with different strangeness.
492 citations
TL;DR: In this paper, the inverse coupling constant of pseudoscalars was shown to be 1 4 gθF F F, where F F F is the number of particles that can be converted to photons in the presence of magnetic fields.
168 citations
TL;DR: In this article, the dominant decay modes of the neutral and charged Higgs bosons in the Minimal Supersymmetric extension of the Standard Model are summarized and analytical expressions for the partial decay widths and the physical implications of these decay modes are discussed.
Abstract: We summarize the dominant decay modes of the neutral and charged Higgs bosons in the Minimal Supersymmetric extension of the Standard Model. While two-body decays are in general dominating, the branching ratios for three-body decays of the heavy scalar, pseudoscalar and charged Higgs bosons can be large below the thresholds if top quarks, W/Z bosons or heavy scalar bosons are involved. Analytical expressions have been derived for the partial decay widths and the physical implications of these decay modes are discussed.
122 citations
TL;DR: In this paper, a complete set of formulas for longitudinal momentum distribution functions (splitting functions) of mesons in the nucleon are presented, which can be applied in the framework of the convolution formalism to the deep-inelastic structure functions (quark distributions) of the nucleus viewed as a system composed of virtual "mesons" and "baryons".
112 citations
TL;DR: In this article, a complete set of formulas for longitudinal momentum distribution functions (splitting functions) of mesons in the nucleon are presented, which can be applied in the framework of convolution formalism to the deep-inelastic structure functions (quark distributions) viewed as a system composed of virtual "mesons" and "baryons".
Abstract: We present a complete set of formulas for longitudinal momentum distribution functions (splitting functions) of mesons in the nucleon. It can be applied in the framework of convolution formalism to the deep-inelastic structure functions (quark distributions) of the nucleon viewed as a system composed of virtual 'mesons' and 'baryons'. Pseudoscalar and vector mesons as well as octet and decuplet baryons are included. In contrast to many approaches in the literature the present approach ensures charge and momentum conservation by the construction. We present not only spin averaged splitting functions but also helicity dependent ones, which can be used to study the spin content of the nucleon. The cut-off parameters of the underlying form factors for different vertices are determined from high-energy particle production data. This information allows one to calculate the flavour and spin content of the nucleon. The value of the Gottfried Sum Rule obtained from our model (S_G = 0.224) nicely agrees with that obtained by the NMC. In addition, we calculate the x-dependence of the \bar d - \bar u asymmetry and get an impressive agreement with a recent fit of Martin-Stirling-Roberts. The calculated axial coupling constants for semileptonic decays of the octet baryons agree with the experimental data already with SU(6) wave function for the bare nucleon. Although we get improvements for the Ellis-Jaffe Sum Rules for the proton and neutron in comparison to the naive quark model, the MCM is not sufficient to reproduce the experimental data.
89 citations
TL;DR: A parameterization of the most general such contributions that can occur when the unbroken gauge symmetry is an arbitrary subgroup of E_6, and how the D-term contributions leave their imprint on physics at ordinary energies is shown.
Abstract: We investigate how the predictions of the Minimal Supersymmetric Standard Model are modified by D-term contributions to soft scalar masses, which arise whenever the rank of the gauge group at very high energies is greater than four. We give a parameterization of the most general such contributions that can occur when the unbroken gauge symmetry is an arbitrary subgroup of E_6, and show how the D-term contributions leave their imprint on physics at ordinary energies. We impose experimental constraints on the resulting parameter space and discuss some features of the resulting supersymmetric spectrum which differ from the predictions obtained with universal boundary conditions on scalar masses near the Planck scale. These include relations between squark and slepton masses; the behavior of $\sin^2 (\beta-\alpha)$ (which determines the production cross-section for the lightest Higgs scalar boson at an e+e- collider) and the mass of the pseudoscalar Higgs bosons; R_b [the ratio $\Gamma(Z -> b\overline b)/\Gamma(Z -> hadrons)$; and mass differences between charginos and neutralinos.
89 citations
TL;DR: A formalism for the relativistic description of hadron decays within the constituent quark model is presented and transition form factors both in the scattering and the decay regions are expressed through light-cone wave functions of the initial and final hadrons.
Abstract: A formalism for the relativistic description of hadron decays within the constituent quark model is presented. First, hadron amplitudes of the light-cone constituent quark model, in particular, the weak transition form factors at spacelike momentum transfers, are represented in the form of dispersion integrals over the hadron mass. Second, the form factors at timelike momentum transfers are obtained by performing the analytic continuation from the region {ital q}{sup 2}{le}0. As a result, the transition form factors both in the scattering and the decay regions are expressed through light-cone wave functions of the initial and final hadrons. The technique is applied to the description of the semileptonic decays of pseudoscalar mesons and direct calculation of the transition form factors at {ital q}{sup 2}{approx_gt}0. Meson properties in the heavy quark limit are investigated. {copyright} {ital 1996 The American Physical Society.}
87 citations
TL;DR: In this paper, the corrections to the current algebra mass formulae for the pseudoscalar mesons are analyzed by means of a simultaneous expansion in powers of the light quark masses and powers of 1 N c.
86 citations
TL;DR: In this article, the cross sections for the multiple production of the lightest neutral Higgs boson at high-energy e + e − colliders are presented in the framework of the Minimal Supersymmetric extension of the Standard Model.
66 citations
TL;DR: In this paper, the authors derived a path integral representation for the effective action of a multiplet of Dirac fermions coupled to the most general set of matrix-valued scalar, pseudoscalar, vector, axial vector and antisymmetric tensor background fields.
66 citations
TL;DR: In this article, a systematic derivation is given of the worldline path integrals for the effective action of a multiplet of Dirac fermions interacting with general matrix-valued classical background scalar, pseudoscalar, and vector gauge fields.
TL;DR: A status report on TRIUMF E452, Radiative Muon Capture on Hydrogen, which is anticipating a 10% measurement of this coupling constant, is presented.
Abstract: Next to the hydrogen atom, the µ − p system is the most fundamental lepton-hadron system; therefore it can be used to test and extend our basic knowledge of the weak semi-leptonic interaction between leptons and quarks. Radiative muon capture (RMC) is much more sensitive than ordinary muon capture (OMC) to the induced pseudoscalar coupling constant of the weak semi-leptonic current because of the much larger range of momentum transfers which can occur in RMC. A status report on TRIUMF E452, Radiative Muon Capture on Hydrogen, which is anticipating a 10% measurement of this coupling constant, is presented.
TL;DR: In this paper, the scalar form factor in τ → Kπντ decays and receives contributions both from scalar resonanceK*0(1430) and from the scalear projection of off-shell vector resonances.
Abstract: We consider the scalar form factor inτ →Kπντ decays. It receives contributions both from the scalar resonanceK*0(1430) and from the scalar projection of off-shell vector resonances. We construct a model for the hadronic current which includes the vector resonancesK*(892) andK*(1410) and the scalar resonanceK*0(1430). The parameters of the model are fixed by matching to theO(p4) predictions of chiral perturbation theory. Suitable angular correlations of theKπ system allow for a model independent separation of the vector and scalar form factor. Numerical results for the relevant structure functions are presented.
TL;DR: It is found that a model that includes only gluon exchange cannot simultaneously describe the Roper and {ital P}-wave excitation energies, and using only pseudoscalar meson exchange partially cures this problem, but at the cost of using a relatively large pion quark coupling constant.
Abstract: We study baryon spectroscopy including the effects of pseudoscalar meson exchange and one gluon exchange potentials between quarks, using nonperturbative, hyperspherical method calculations. We find that a model that includes only gluon exchange cannot simultaneously describe the Roper and {ital P}-wave excitation energies. Using only pseudoscalar meson exchange partially cures this problem, but at the cost of using a relatively large pion quark coupling constant. However, one gets a similar agreement with data in a model with both effects by using a quark-meson coupling constant compatible with the measured pion-nucleon coupling constant, and a value of {alpha}{sub {ital s}}{approx_equal}0.35. {copyright} {ital 1996 The American Physical Society.}
TL;DR: Decays of the D mesons to two pseudosCalars, to two vectors, and to pseudoscalar plus vector are discussed in the context of broken flavor SU(3) to reduce the number of parameters.
Abstract: Decays of the D mesons to two pseudoscalars, to two vectors, and to pseudoscalar plus vector are discussed in the context of broken flavor SU(3). A few assumptions are used to reduce the number of parameters. Amplitudes are fit to the available data, and predictions of branching ratios for unmeasured modes are made.
TL;DR: In this article, it was shown that the effective chiral Lagrangian of the strong and electromagnetic interactions of the pseudoscalar mesons at low energies depends on a set of low energy constants.
Abstract: The effective chiral Lagrangian of the strong and electromagnetic interactions of the pseudoscalar mesons at low energies depends on a set of low energy constants. We determine the contributions to the electromagnetic coupling constants at order $O(e^2 p^2)$, which arise from resonances within a photon loop. We give some implications of our results, in particular we discuss in detail the effects on the corrections to Dashen's theorem.
TL;DR: In this article, the transition form factors of heavy pseudoscalar mesons were investigated in a relativistic constituent quark model formulated on the light-front, and the results were consistent with available experimental data and predictions of lattice QCD calculations and QCD sum rules.
TL;DR: In this article, the intrinsic electromagnetic nuclear meson exchange charge and current operators arising from a separation of the center-of-mass motion are derived for a one-boson-exchange model for the nuclear interaction with scalar, pseudoscalar and vector meson exchanges including leading order relativistic terms.
Abstract: The intrinsic electromagnetic nuclear meson exchange charge and current operators arising from a separation of the center-of-mass motion are derived for a one-boson-exchange model for the nuclear interaction with scalar, pseudoscalar and vector meson exchange including leading order relativistic terms. Explicit expressions for the meson exchange operators corresponding to the different meson types are given in detail for a two-nucleon system. These intrinsic operators are to be evaluated between intrinsic wave functions in their center-of-mass frame.
CERN1
TL;DR: In this paper, the present status of lattice gauge theory computations of the leptonic decay constants f D and f b is summarized and various sources of systematic errors are explained in a manner easily understood by the non-expert.
TL;DR: In this article, the effects of pseudoscalar meson exchange and one gluon exchange potentials between quarks, governed by α s, were studied in baryon spectroscopy.
Abstract: We study baryon spectroscopy including the effects of pseudoscalar meson exchange and one gluon exchange potentials between quarks, governed by $\alpha_s$. The non-perturbative, hyperspherical method calculations show that one can obtain a good description of the data by using a quark-meson coupling constant that is compatible with the measured pion-nucleon coupling constant, and a reasonably small value of $\alpha_s$.
TL;DR: In this article, the authors investigated the detection of a pseudoscalar φ that couples electromagnetically via an interaction 1 4 gφF F, and found that the sun's external magnetic dipole field and sunspot-related magnetic fields were superior.
TL;DR: In this paper, the pseudoscalar and pseudovector ηN coupling constants are calculated from an effective vertex associated with the a0(980)πN triangle diagram, and the predicted values are in agreement with the ones concluded from fitting η photoproduction amplitudes.
TL;DR: It is shown that the QCD anomaly may lead to an abnormal mixing behavior of the axial vector mesons similar to the pseudoscalar mesons, which generates a nonvanishing strange quark component in the nucleon.
Abstract: It is shown that the QCD anomaly may lead to an abnormal mixing behavior of the axial vector mesons similar to the pseudoscalar mesons. These mixing effects, involving a gluonic axial vector state, generate a nonvanishing strange quark component in the nucleon. They reduce the matrix element of the singlet axial vector in comparison to the value obtained in a naive quark model. The results are in agreement with the data obtained in the polarized lepton-nucleon scattering experiments. {copyright} {ital 1996 The American Physical Society.}
01 Jun 1996
TL;DR: In this paper, the authors investigated the radiative decays of pseudoscalar, vector and axial vector mesons using a simple relativistic constituent quark model.
Abstract: The authors investigate the radiative decays of pseudoscalar ({pi}, {Kappa}, {eta}, {eta}{prime}), vector ({rho}, {Kappa}{sup *}, {omega}, {phi}) and axial vector ({Alpha}{sub 1}) mesons using a simple relativistic constituent quark model. For both simplicity and relativity, they take advantage of the distinguished features in the light-cone quantization method; (1) the Fock-state expansion of meson wavefunctions are not contaminated by the vacuum fluctuation, (2) the problem of assigning quantum numbers J{sup PC} to mesons is circumvented by the Melosh transformation. Except the well-known constituent quark masses of (u,d,s) quarks and the spin-averaged meson masses, the only parameter in the model is the gaussian parameter Beta which determines the broadness (or sharpness) of radial wavefunction. Their overall predictions of pseudoscalar, vector and axial vector meson radiative decay processes are remarkably in a good agreement with the experimental data.
TL;DR: This work derives the kinetic equations for both the covariant and equal-time Wigner functions of Dirac particles with electromagnetic, scalar and pseudoscalar interactions with constraint equations for the spinor components in the equal- time formulation.
Abstract: We derive the kinetic equations for both the covariant and equal-time Wigner functions of Dirac particles with electromagnetic, scalar and pseudoscalar interactions. We emphasize the constraint equations for the spinor components in the equal-time formulation.
TL;DR: In this paper, the authors evaluate the π 0 γ ∗ → γ transition form factor and γγ decay widths for π, η c and η b treated as q q bound states in the Bethe-Salpeter formalism, incorporating the dynamical chiral symmetry breaking and the Goldstone nature of the pion.
TL;DR: New, more restrictive bounds on photon-massless-pseudoscalar coupling are discussed and it is suggested that the maximum value of the Higgs boson may be below that of the proton-proton collision.
Abstract: New, more restrictive bounds on photon-massless-pseudoscalar coupling are discussed. {copyright} {ital 1996 The American Physical Society.}
TL;DR: In this paper, the scalar representations of the electroweak group of the Standard Model were studied, which is a subgroup of the chiral group U(N) l × U(n) r with N flavors, for N even, with a special emphasis on their chiral properties and on their behaviour by the discrete symmetries P and CP.
TL;DR: In this paper, the pseudoscalar and pseudovector coupling constants are calculated from an effective vertex associated with the $a_0(980)pi N$ triangle diagram, and the predicted values are in agreement with the ones concluded from fitting $\eta $ photoproduction amplitudes.
Abstract: The pseudoscalar and pseudovector $\eta N$ coupling constants are calculated from an effective vertex associated with the $a_0(980)\pi N$ triangle diagram. The predicted values are in agreement with the ones concluded from fitting $\eta $ photoproduction amplitudes. In this context we stress the importance of the properties of the scalar meson octet for $\eta $ meson physics.
TL;DR: In this article, the space-like elastic form factor of heavy-light pseudoscalar mesons is investigated within a light-front constituent quark model in order to evaluate the Isgur-Wise form factor.