Showing papers on "Meson published in 1985"
TL;DR: In this article, the formfactors of the hadronic current in terms of relativistic bound state wave functions for which they take the solutions of a relativistically harmonic oscillator potential were derived.
Abstract: Exclusive semileptonic decays of heavy mesons provide interesting information on systems consisting of quarks of unequal mass. We express the formfactors of the hadronic current in terms of relativistic bound state wave functions for which we take the solutions of a relativistic harmonic oscillator potential. The wave function overlap is determined by the quark mass dependent longitudinal momentum distribution and differs from results based on non relativistic wave functions. The semileptonic widths and lepton spectra are calculated using in addition nearest pole dominance for the momentum transfer dependence of the formfactors. We compare our results with recent experimental data. The formfactor calculation also allows an estimate of special nonleptonic transitions. From the CLEO results on\(\bar B^0 \to \pi ^ + \pi ^ -\) and\(\bar B^0 \to D^{* + } + \pi ^ -\) we find for the corresponding Kobayashi-Maskawa matrix element ratio the limit |V ub /V cb |≲0.3.
721 citations
TL;DR: In this paper, the Lagrangian field theory of interacting nucleons, hyperons, and mesons is applied to neutron stars in the mean field approximation to account for the four bulk properties of nuclear matter; saturation binding and density, compressibility, and charge symmetry energy.
Abstract: Neutron stars are studied in the framework of Lagrangian field theory of interacting nucleons, hyperons, and mesons, which is solved in the mean field approximation The theory is constrained to account for the four bulk properties of nuclear matter; the saturation binding and density, compressibility, and charge symmetry energy The cores of the heavier neutron stars are found to be dominated by hyperons, and the total hyperon population for such stars is 15%--20%, depending on whether pions condense or not The rho-meson, which contributes to the isospin symmetry energy, has an important influence on the baryon populations Lepton populations are strongly suppressed and charge neutrality is achieved among the hadrons A possible consequence for the decay time of the magnetic field of pulsars and hence for their active lifetime is mentioned
574 citations
TL;DR: In this article, the authors calculate the corrections to various low-energy theorems concerning the behavior of pseudoscalar meson form factors near t = 0, including the Ademollo-Gatto theorem, Sirlin's relation between the Kl3 form factor ƒ+Kπ(t) and the electromagnetic form factors, and Dashen-Weinstein relation.
469 citations
TL;DR: In this article, the authors analyzed the electromagnetic leptonic decays of light mesons and proposed ways of using these processes for extracting information on the transition form factors of neutral mesons.
297 citations
TL;DR: In this article, the pion electromagnetic form factor has been measured at the VEPP-2M collider in the c.m. energy range 360 MeV-1400 MeV with the detectors OLYA and CMD.
295 citations
TL;DR: In this article, it was shown that baryons carrying heavy flavors, such as strangeness and charm, can be described by bound states of the corresponding heavy mesons in the background field of the basic SU(2) skyrmion.
260 citations
TL;DR: In this paper, the Wess-Zumino anomaly equation was solved by incorporating vector mesons as dynamical gauge bosons of the hidden local symmetry in the nonlinear chiral Lagrangian.
Abstract: We present general solutions to the Wess-Zumino anomaly equation which incorporate vector mesons as dynamical gauge bosons of the hidden local symmetry in the nonlinear chiral Lagrangian. In contrast to the previous attempts to introduce the vector mesons, our formalism enables one to treat consistently and systematically various processes associated with pseudoscalar mesons (Nambu-Goldsone bosons) and vector mesons (dynamical gauge bosons); it is automatic in this framework that the on-shell amplitudes of photons and pseudoscalar mesons such as π^0 →2γ and γ→3 π which are fixed by the low energy theorems, are not affected no matter how the vector mesons participate in those processes. We further show that the “complete vector meson dominance” hypothesis of photon couplings is invalid in either π^0 →2γ or γ→3π process.
226 citations
TL;DR: Specific predictions of decay channels which will contain JPC exotic hybrid resonance signals are made and some possibly fruitful production mechanisms are suggested.
Abstract: We have studied the decays of the low‐lying gluonic excitations of mesons (hybrids) predicted by a flux tube model for chromodynamics. The probable reason for the absence to data of signals for such states is immediately explained: the lowest lying hybrids decay preferentially to final states with one excited meson (e.g., B(1235)π, A2(1320)π, K*(1420)K, π(1300)π,...) rather than to two ground state mesons (e.g., ππ, ρπ, K*K,...). We make specific predictions of decay channels which will contain JPC exotic hybrid resonance signals and suggest some possibly fruitful production mechanisms.
213 citations
TL;DR: In this article, it was shown that vector mesons are dynamical gauge bosons of the hidden local symmetry in the U(3)L × U (3)R/U(3)-v nonlinear sigma model.
210 citations
TL;DR: In this paper, the properties of the heavy fragment nuclei (A ≥ 10.5 GeV/u) are analyzed in the framework of models for spallation, fission and multifragmentation.
195 citations
TL;DR: The formation of the quark-gluon plasma in relativistic nuclear collisions may be determined by enhanced production of $\ensuremath{\varphi}$ mesons, which will not rescatter significantly in the subsequent expanding hadronic phase and would thereby retain information on the conditions of the hot plasma.
Abstract: The formation of the quark-gluon plasma in relativistic nuclear collisions may be determined by enhanced production of $\ensuremath{\varphi}$ mesons. This enhancement would result from the absence of the Okubo-Zweig-Iizuka suppression which inhibits $\ensuremath{\varphi}$ production in ordinary $p\ensuremath{-}p$ and $\ensuremath{\pi}\ensuremath{-}p$ collisions, and from a large abundance of strange quarks in the plasma. The $\ensuremath{\varphi}$ will not rescatter significantly in the subsequent expanding hadronic phase and would thereby retain information on the conditions of the hot plasma.
TL;DR: In this paper, an extended vector dominance model which incorporates quark dynamics at largeQ2 via perturbative QCD gives an excellent description of existing data on elastic electron-proton/neutron cross-sections.
Abstract: We show that an extended vector dominance model which incorporates quark dynamics at largeQ2 via perturbative QCD gives an excellent description of existing data on elastic electron-proton/neutron cross-sections Results of a simultaneous fit of the nucleon form factorsGM,Ep,n to the cross-sections are given Information is obtained about the QCD-scale parameterΛQCD, as well as on the range of applicability of perturbative QCD calculations Constraints on the hadronic wavefunctions are also obtained
TL;DR: It is shown that, to quadratic order in meson masses, the amplitude for K→2π can be written in terms of the unphysical amplitudes K→π and K→0, where 0 is the vacuum, and the reason for the presence of the K→ 0 amplitude is explained.
Abstract: Chiral perturbation theory is applied to the decay K→2π. It is shown that, to quadratic order in meson masses, the amplitude for K→2π can be written in terms of the unphysical amplitudes K→π and K→0, where 0 is the vacuum. One may then hope to calculate these two simpler amplitudes with lattice Monte Carlo techniques, and thereby gain understanding of the ΔI=1/2 rule in K decay. The reason for the presence of the K→0 amplitude is explained: it serves to cancel off unwanted renormalization contributions to K→π. We make a rough test of the practicability of these ideas in Monte Carlo studies. We also describe a method for evaluating meson decay constants which does not require a determination of the quark masses.
TL;DR: In this article, it was shown that the EMC-effect can be explained by the nuclear structure and that the binding of nucleons played an important role in the nuclear EMC effect.
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TL;DR: In this paper, the Skyrme effective lagrangian is generalized to include a term simulating the effects of ω mesons and it is possible to reproduce a number of properties of single baryons and of the central NN interaction in a manner which is both qualitatively appealing and quantitatively satisfactory.
TL;DR: For neutrino mass eigenstates v i of mass between 0.5 and 1.75 GeV, it was shown in this article that neutrinos can be produced through mixing in charmed D meson decays.
TL;DR: The meson spectrum in a model with a confining Lorentz-vector is studied and it is found that the pion satisfies the expected dispersion law for a Goldstone boson, f/sub piprime/ = 0 in the chiral limit, where ..pi..' is any radially excited pion.
Abstract: We study the meson spectrum in a model with a confining Lorentz-vector: and hence chiral-invariant: interaction between massless quark fields. As shown in a previous work, chiral invariance is spontaneously broken. In the case of the harmonic oscillator, as the Fourier transform of the potential is the Laplacian of a delta function, the Bethe-Salpeter (BS) equation: a system of linear integral equations in general: splits into a system of differential equations that we solve in the broken vacuum. Without appealing to any spin-spin interaction, we find, besides the massless pseudoscalar, a vector meson at the right scale and an excited pion and two vectors in the 1--2-GeV region. Moreover, we find a large L-S splitting with the expected ordering for a vector interaction. We study in detail the BS wave function for the pion in motion, necessary to compute axial-vector-current matrix elements, and recover well known relations of current algebra. We compute f/sub ..pi../ and find on general grounds that f/sub piprime/ = 0 in the chiral limit, where ..pi..' is any radially excited pion. The pion satisfies the expected dispersion law for a Goldstone boson, ..omega..(p)..-->..cp (p..-->..0). .AE
TL;DR: In this article, the low energy lagrangian for light pseudoscalar mesons is obtained from chiral symmetry breaking components of the effective action of QCD, essentially determined by non-topological anomalies.
TL;DR: A parity-invariant chiral Lagrangian is formulated which includes nonlinearly transforming vector mesons but no axial-vector mesons, and the prototype anomalous strong decay is discussed.
Abstract: We formulate a parity-invariant chiral Lagrangian which includes nonlinearly transforming vector mesons but no axial-vector mesons. It is gotten by a simple substitution from the Lagrangian involving a linearly transforming vector and axial-vector multiplet. This feature makes it easy to apply in the case when a gauged Wess-Zumino term is present, and we discuss the prototype anomalous strong decay \ensuremath{\omega}\ensuremath{\rightarrow}3\ensuremath{\pi}. .AE
TL;DR: In this paper, a Wess-Zumino chiral effective action describes the low-lying mesons and baryons, which appear as solitons, as a dynamical result of QCD in two dimensions.
TL;DR: In this paper, a model for the fragmentation of heavy quarks is proposed, based on a scheme used previously to calculate hadron structure functions, which embodies the hardness expected from the decay kinematics, and is consistent with'reciprocity', which demands that the fragmentation function should be related to the hadronic structure function.
Abstract: A model for the fragmentation of heavy quarks is proposed, based on a scheme used previously to calculate hadron structure functions. It embodies the hardness expected from the decay kinematics, and is consistent with 'reciprocity', which demands that the fragmentation function should be related to the hadronic structure function. It agrees with the data on c and b quark fragmentation, but its predictions for t and other very heavy quarks are significantly different from the model of Peterson et al., (1983), for example.
TL;DR: In this article, the contributions of meson exchange currents and final state interactions to the longitudinal and transverse response functions of 3 He were estimated, and they improved their usual one-body descriptions.
TL;DR: Miyazawa's supersymmetric generalization of the approximate SU 6/21 symmetry of hadrons is shown to hold in the same approximation for which SU 6 is a good symmetry, provided a diquark structure emerges through an effective string interaction as mentioned in this paper.
Abstract: Miyazawa's supersymmetric generalization of the approximateSU
6 symmetry of hadrons, namelyU
6/21, is shown to arise within the frame of the standard theory of quarks interacting through gluons. The supersymmetry is found to hold in the same approximation for whichSU
6 is a good symmetry, provided a diquark structure emerges through an effective string interaction. The spin independence of the confining force of the strong-coupling regime then explains the near parallelism of the leading Regge trajectories for baryons and mesons. Symmetry breaking is due to mass differences of the constituents and spin-dependent forces caused by gluon exchange. TheU
6/21 algebra is also shown to be embedded in a larger octonionic algebra which puts mesons and baryons, exotic mesons, quarks and diquarks in the same multiplet. The experimental evidence for the existence of qq and
$$qq\overline {qq} $$
systems is briefly discussed.
TL;DR: The first results from a small-lattice calculation of nonleptonic weak matrix elements are presented, finding a significantly enhanced $\ensuremath{\Delta}I=\frac{1}{2}$ amplitude and a $\ensUREmath{3}{2]$ amplitude compatible with zero within the authors' statistics.
Abstract: We present the first results from a small-lattice (${6}^{3}$ \ifmmode\times\else\texttimes\fi{} 10) calculation of nonleptonic weak matrix elements. The $\ensuremath{\Delta}I=\frac{1}{2}$ rule is studied as a test case. For a lattice meson of approximately the kaon mass we find a significantly enhanced $\ensuremath{\Delta}I=\frac{1}{2}$ amplitude and a $\ensuremath{\Delta}I=\frac{3}{2}$ amplitude compatible with zero within our statistics. The dominance of the $\ensuremath{\Delta}I=\frac{1}{2}$ amplitude appears to be due to a class of graphs called the eye graphs. Qualitatively similar results are found whether or not the charm quark is integrated out ab initio. We also report preliminary results on other weak matrix elements.
TL;DR: In this article, a study of multimuon events obtained in a high luminosity proton-platinum experiment at 400 GeV/c was conducted, and the authors found 5 ± 4 ψψ events, which correspond to a production cross section σ ( ψ ψ = 27 ± 10 pb).
TL;DR: In this article, the authors studied the hadronic decay of q\(\bar q\)g hybrid mesons and established the connection between the diatomic-molecule like wave functions and the standard q\(bar q\g wave functions.
Abstract: We study the hadronic decay of q\(\bar q\)g hybrid mesons. To that aim we establish the connection between the diatomic-molecule like wave functions and the standard q\(\bar q\)g wave functions. We show that inSU(6) approximation TE hybrids cannot decay intoPP, PV, VV channels while TM hybrids are weakly coupled to ψγ. Hence only TE-TM mixed hybrids are easy to see in ψ → γX. We show that hydrids are weakly mixed with quarkonia. We discuss the possible nature of the ξ(2.2) resonance and the ways of detecting exotic 1−+ q\(\bar q\)g bound states.
CERN1
TL;DR: In this article, it was shown that the realistic baryon mass spectrum in the SU(3) Skyrme model with massive 0− mesons can be obtained only for Fπ m δ ∗ and obtain baryons within the limits of ± 16% of the experimental val ues, but at the expense of very low ifFπ=46.32 MeV.
TL;DR: In this article, the average transverse momentum is found to be 〈pT〉 = 0.57±0.03 GeV/c in the rapidity range |y| in the CERN SPS p p Collider.
TL;DR: In this article, the authors studied both states with equal mass quarks and open flavour states for J = 0 and 1 with all possible combinations for the P and C quantum numbers, including several exotic combinations.