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Showing papers on "Meson published in 1980"


Journal ArticleDOI
TL;DR: In this article, a systematic analysis in perturbative quantum chromodynamics (QCD) of large-momentum-transfer exclusive processes is presented, where the scaling behavior, angular dependence, helicity structure, and normalization of elastic and inelastic form factors and large-angle exclusive scattering amplitudes for hadrons and photons are given.
Abstract: We present a systematic analysis in perturbative quantum chromodynamics (QCD) of large-momentum-transfer exclusive processes. Predictions are given for the scaling behavior, angular dependence, helicity structure, and normalization of elastic and inelastic form factors and large-angle exclusive scattering amplitudes for hadrons and photons. We prove that these reactions are dominated by quark and gluon subprocesses at short distances, and thus that the dimensional-counting rules for the power-law falloff of these amplitudes with momentum transfer are rigorous predictions of QCD, modulo calculable logarithmic corrections from the behavior of the hadronic wave functions at short distances. These anomalous-dimension corrections are determined by evolution equations for process-independent meson and baryon "distribution amplitudes" $\ensuremath{\varphi}({x}_{i}, Q)$ which control the valence-quark distributions in high-momentum-transfer exclusive reactions. The analysis can be carried out systematically in powers of ${\ensuremath{\alpha}}_{s}({Q}^{2})$, the QCD running coupling constant. Although the calculations are most conveniently carried out using light-cone perturbation theory and the light-cone gauge, we also present a gauge-independent analysis and relate the distribution amplitude to a gauge-invariant Bethe-Salpeter amplitude.

2,239 citations


Journal ArticleDOI
TL;DR: In this paper, the pseudoscalar and photon couplings of the states associated with up to two orbital or one radial excitation in the nonrelativistic quark model are used to generate a set of baryon amplitudes which resolve the problem of "missing" resonances by essentially decoupling a very large number of states from partial-wave analyses and leaving those resonances which remain in remarkable correspondence to the observed states in both their masses and decay amplitudes.
Abstract: Quark models of hadrons are tested in a very limited way when only their spectroscopy is compared with experiment; at least equally important tests arise from examining the predicted internal structure of the hadrons via analysis of their decay amplitudes. We present here a compilation of one of the most extensive calculations of baryon amplitudes to date, encompassing the pseudoscalar and photon couplings of the states associated with up to two orbital or one radial excitation in the nonrelativistic quark model. These amplitudes are then combined with the baryon compositions predicted by a quark model incorporating some of the features expected to arise from quantum chromodynamics. The result is to generate a set of baryon amplitudes which (1) resolve the problem of "missing" resonances by essentially decoupling a very large number of states from partial-wave analyses and (2) leave those resonances which remain in remarkable correspondence to the observed states in both their masses and decay amplitudes.

260 citations


Journal ArticleDOI
TL;DR: In this article, the authors examined the experimental prospects for detecting spin-parity onium states which are otherwise difficult to reach or discovering Higgs mesons and concluded that these prospects are not very bright.

180 citations


Journal ArticleDOI
TL;DR: In this paper, an asymmetry in the combined multiplicity aand angular distributions of the final state mesons in a quark-antiquark-gluon fragmentation event from e + e − annihilation was pointed out.

136 citations


Journal ArticleDOI
TL;DR: In this article, the anomalous dimension of nonsinglet structure functions is compared to a corresponding logarithmic correction factor to the nominal α S (Q 2 )/Q 2 fall off of meson form factors.

129 citations


Journal ArticleDOI
TL;DR: The strong chiral symmetry breaking in Wilson's lattice version of QCD is discussed and interpreted as a necessary manifestation of the triangle anomaly in this paper, where the effective hamiltonian acting in the s-wave hadron sector is found to describe a generalized antiferromagnet.

117 citations


Journal ArticleDOI
TL;DR: In this article, a potential model based on quantum-chromodynamics (QCD) considerations is developed, which attempts to overcome the relativistic limitations associated with earlier models by introducing an effective size for quarks.
Abstract: A potential model based on quantum-chromodynamics (QCD) considerations is developed. The model attempts to overcome the relativistic limitations associated with earlier models by introducing an effective size for quarks. Application of the model Hamiltonian to both light and heavy mesons yields an accurate description of the mass spectrum, radiative transitions, and annihilation widths for a large number of known mesons. Spin-dependent interactions are treated nonperturbatively using standard diagonalization procedures with an oscillator basis set and relativistic kinematics are adopted throughout. The scaling of the potential parameters is found to be similar to simple QCD predictions. Much of the anomalous behavior for pseudoscalar mesons appears to be resolved both for light and heavy mesons.

110 citations


Journal ArticleDOI
TL;DR: In this paper, the quark and antiquark joint distribution is derived systematically with incorporation of quantum-chromodynamics ideas whenever possible, and parameters describing the distribution are determined by fitting low-$Q}^{2}$ electroproduction data.
Abstract: The low-${p}_{T}$ problem of hadron fragmentation is treated in the framework of the quark model. The basic mechanism of hadronization of quarks is recombination, which is formulated here on a firm basis. Clustering of quarks in a hadron is discussed in detail. The quark and antiquark joint distribution is derived systematically with incorporation of quantum-chromodynamics ideas wherever possible. Parameters describing the distribution are determined by fitting low-${Q}^{2}$ electroproduction data. No free parameters are therefore involved in the calculation of the pion inclusive distribution in the fragmentation region. The result agrees well with data in both shape and normalization. The formalism can be applied to calculate inclusive distributions of all nucleon- and pion-initiated reactions, while for kaon-initiated reactions it can be used to extract from low-${p}_{T}$ data the quark distributions in kaons.

104 citations


Journal ArticleDOI
TL;DR: In this paper, the authors derived constraints on charged-Higgs-boson couplings in gauge theories of the weak and electromagnetic interactions using the experimental value of the KL-KS mass difference.
Abstract: Using the experimental value of the KL-KS mass difference, the authors derive constraints on charged-Higgs-boson couplings in gauge theories of the weak and electromagnetic interactions. These bounds severely restrict the possible magnitude of charged-Higgs-boson effects in K and D meson decays. The results are based on the observation that charged-Higgs-boson-exchange contributions to K0-K0 mixing are of order 1/MH^2 whereas the corresponding W-boson contribution is only of order mc^2/MW^4.

101 citations


Journal ArticleDOI
TL;DR: In this paper, the meson electromagnetic form factor was shown to satisfy the Callan-Symanzik equation and is given by independent light-cone expansions on the initial and final meson legs.
Abstract: Composite-particle form factors are studied in the limit of large momentum transfer Q. It is shown that in models with spinor constituents and either scalar or gauge vector gluons, the meson electromagnetic form factor factorizes at large Q/sup 2/ and is given by independent light-cone expansions on the initial and final meson legs. The coefficient functions are shown to satisfy a Callan-Symanzik equation. When specialized to quantum chromodynamics, this equation leads to the asymptotic formula of Brodsky and Lepage for the pion electromagnetic form factor. The nucleon form factors G/sub M/(Q/sup 2/), G/sub E/(Q/sup 2/) are also considered. It is shown that momentum flows which contribute to subdominant logarithms in G/sub M/(Q/sup 2/) vitiate a conventional renormalization-group interpretation for this form factor. For large Q/sup 2/, the electric form factor G/sub E/(Q/sup 2/) fails to factorize, so that a renormalization-group treatment seems even more unlikely in this case.

99 citations


Journal ArticleDOI
TL;DR: In this article, momentum-space wave packets are used to approximate the mass of the pion in the bag model, and the formula m/sub q/=(m-italic/sub u/+m/sub d/)/2=33 MeV is derived.
Abstract: Quark-model calculations involve an extended static object localized in space. We introduce new methods, involving momentum-space wave packets, which account for this localization. These methods have little effect on heavy states, whose sizes are large compared to their Compton size 1/m, but are very important for light particles such as the pion. In this treatment the pion's mass is naturally very small, and, in order to connect with a spontaneously broken chiral symmetry, we require that m/sub ..pi../ vanish when the light quarks are massless. Expanding about this limit (and also readjusting the fit to other hadrons), we obtain m/sub q/=(m-italic/sub u/+m/sub d/)/2=33 MeV. We calculate F/sub ..pi../ approx. = 145 MeV (using a normalization such that F/sub ..pi../ vertical-bar /sub exp/=93 MeV), F/sub K//F/sub ..pi../ approx. = 1, and various corrections to static properties of baryons. In addition we explore the relationship of our methods with chiral perturbation theory, deriving the formula m/sub ..pi../ /sup 2/=(m-italic/sub u/+m/sub d/) in the appropriate approximation and commenting on the quark mass obtained from the nucleon's sigma term. Finally we discuss the bag model's use of the scalar density q-barq as an order parameter describing themore » separation of the spontaneously broken vacuum phase from the perturbative vacuum of the bag's interior.« less

Journal ArticleDOI
TL;DR: In this paper, it was shown that the non-leptonic decays of mesons proceed via the annihilation of a vectorial color octet quark-anti-quark configuration.

Book
01 Jan 1980
TL;DR: In this paper, Meson interactions with nucleons, mesons and deuterons: three-body systems, Mesons and nuclei: multiple scattering theory, Meson scattering by nuclei, applications of multiple scattering theories; Field theory and coupled channel methods; Absorption and production of mesons; Meson interaction and nuclear structure.
Abstract: This book covers the following topics: Meson interactions with nucleons; Mesons and deuterons: three-body systems; Mesons and nuclei: multiple scattering theory; Meson scattering by nuclei: applications of multiple scattering theory; Field theory and coupled channel methods; Absorption and production of mesons; Meson interactions and nuclear structure.

Journal ArticleDOI
TL;DR: In this article, it was shown that in the dilute instanton gas approximation for quarks in the external instanton field Πsu = 0 for the vector and tensor currents and ΠSu≠0 for the axial current.

Journal ArticleDOI
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.

Journal ArticleDOI
TL;DR: In this article, a special choice of gauge QCD2 [SU(N)] with one flavor of quarks is recast into the Bose form, which is shown to be the SU(N)-symmetric confining phase in which bound states possess stringlike configurations with strings being represented by electric vortex lines.

Journal ArticleDOI
TL;DR: In this article, the E(1420) meson was investigated in a high statistics (90 events/μb) bubble chamber experiment and the results showed that the meson achieved a branching ratio of 0.95 GeV/c.

Journal ArticleDOI
Hartmut Krasemann1
TL;DR: In this paper, a refinement of the Van Royen-Weisskopf formula was used to calculate the decay constants of all known vector mesons within a standard QCD based potential model.

Journal ArticleDOI
TL;DR: In this paper, total and annihilation cross sections for p-barp and p-bard have been measured over the momentum range 355-1066 MeV/c at closely spaced momenta and with good energy resolution.
Abstract: Total and annihilation cross sections for p-barp and p-bard have been measured over the momentum range 355--1066 MeV/c at closely spaced momenta and with good energy resolution. No evidence is seen for the narrow structure reported by other experiments in the vicinity of 500 MeV/c. The present measurements indicate a broader enhancement in this region, which, if interpreted as a resonance, would have a height of approx. 3 mb and a width of approx. 20 MeV. This structure appears only in the p-barp data.

Journal ArticleDOI
TL;DR: In this paper, the effective Hamiltonian applicable to such decays is calculated in leading-logarithmic approximation and attention is focused on the magnitude of CP-violating effects.
Abstract: The decay K→πe+e- is considered in the six-quark model. The effective Hamiltonian applicable to such decays is calculated in leading-logarithmic approximation and attention is focused on the magnitude of CP-violating effects.

Journal ArticleDOI
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.

Book ChapterDOI
01 Jan 1980
TL;DR: A review of recent developments of the bag-based model can be found in this paper, with a brief introduction to the model in the static cavity approximation and a discussion of deformations applied to a calculation of the electric polarizability of the π meson and applied to rotationally excited states.
Abstract: Since its formulation in 1974, the MIT bag model in various versions has acquired a considerable following. It is neither possible nor desirable for me to attempt to review all of the bag related developments of the past five years. A few works of a review nature exist. These are listed in Ref. 1–4. I shall give a brief introduction to the model in the static cavity approximation, since this approach has been the starting point for many applications. Following this is a discussion of deformations of the bag, applied to a calculation of the electric polarizability of the π meson, and applied to rotationally excited states. Some recent results regarding hadronic interactions are reviewed, in particular, for low energy nucleon-nucleon interactions and for meson-meson interactions. Finally, I shall discuss some recent efforts at treating low energy pion interactions in the bag model using PCAC.

Journal ArticleDOI
TL;DR: In this paper, the branching ratio of the rare electromagnetic decay η → μ+μ−γ has been measured as BR(η → δ) = (3.1 ± 0.4) × 10−4.

Journal ArticleDOI
TL;DR: In this paper, the authors suggest that final state soft gluon exchange may account for the rather large branching ratio recently measured for this process, and study two-body decays of charmed mesons in a new scheme.

Journal ArticleDOI
TL;DR: In this paper, it was shown that 1/Q2 higher-twist terms are dominant in well defined kinematic regions such as largex and/or largez.
Abstract: Inclusion of specific effects associated with constituent binding in hadronic wave functions is shown to lead to important non-scaling, nonfactorizing 1/Q2 contributions to cross sections for semi-inclusive deep-inelastic scattering, the Drell-Yan process, and other hard scattering reactions. These 1/Q2 higher-twist terms are predicted to be dominant in well defined kinematic regions such as largex and/or largez. The provide angular distributions typical of longitudinally polarized virtual photons andW's, including sin2 θ terms in meson induced Drell-Yan processes and ine+e−→πX, as well as unusual (1−y) terms in deep-inelastic scattering. Calculations are also presented of the quark structure functions of the pionqπ(x, Q2) and for the quark to pion fragmentation functionDπ(z, Q2). Predictions are made for the azimuthal angle dependence of the cross sections for\(\pi N \to \mu {\text{ }}\bar \mu X\) andlN→l′πX.

Journal ArticleDOI
TL;DR: In this paper, a set of constraints on the masses of particles in the Weinberg-Salam model is obtained and it is shown that in the absence of superheavy fermions (m F ≲ 100 GeV) the Higgs meson mass should exceed the Coleman-Weinberg value ≈9.2 GeV for sin 2 φW ≈ 0.23.

Journal ArticleDOI
TL;DR: In this article, the Paris NN interaction was used to obtain σtot and dσ dΩ for π+d/a3pp with the most recent version of the Paris nN interaction.

Journal ArticleDOI
TL;DR: In this article, relativistic and zero point energy corrections are shown to be absorbed in renormalizing phenomenological quark mass parameters appearing in quark model descriptions of baryon and meson masses.

01 Jun 1980
TL;DR: In this article, the differential and integrated spectra of neutrinos generated in the atmosphere for the energy range 10--10/sup 7/GeV were calculated using the inclusive cross sections for pion and kaon generation obtained in accelerator experiments for pp interactions.
Abstract: We give the differential and integrated spectra of neutrinos generated in the atmosphere for the energy range 10--10/sup 7/ GeV. The calculations are carried out using the inclusive cross sections for pion and kaon generation obtained in accelerator experiments for pp interactions. The applicability of these data in the fragmentation region for energies up to 10/sup 4/--10/sup 5/ GeV was verified experimentally using data on cosmic ray muons. The problem of a contribution from prompt neutrinos to the fluxes of atmospheric neutrinos is discussed. A number of other characteristics of atmospheric neutrino fluxes are considered. Analytic approximations are given for the calculated neutrino spectra.

Journal ArticleDOI
TL;DR: In a second beam-dump experiment using BEBC the prompt neutrino flux has been measured and its characteristics studied as discussed by the authors, and an upper limit of 10% can be set to the proportion of interactions induced by τ neutrinos.