Problems with the ω′(1.78) vector meson

We discuss the properties of the ω′(1.78) as compared to those of the ?′(1.55) (mass, width, decay modes, couplings to the photon, intensity of the cross-section) in the framework of the quark model and of VDM. Special attention is paid to the ω′??′ mixing problem and the applicability of the Zweig rule; predictions for a ?′ are given.     

SU(3) breaking in the two-body decays of the Ψ(3100)

Motivated by the experimental fact that the ψ(3100) does not appear to behave like an SU(3) singlet when it decays into a vector pseudoscalar final state, we propose a model for SU(3) breaking in ψ decays. In the model we envision the ψ decay as a two-stage'process. In the first stage the quark-antiquark pair which comprises the ψ annihilate via a Zweig rule violating interaction to create a pair of “ordinary” quarks. We allow this interaction to violate SU(3) invariance so that all quarks may not be created equally. In stage two the quark pair turns itself into hadrons via a Zweig-allowed, SU(3)-invariant interaction. The data for the vector-pseudoscalar decays seem to indicate that the intermediate quark pair behaves like a heavy ω. We then use this “fact”. to make predictions for the baryon-antibaryon and the tensor-vector decays.     

Low-energy ππ and πK scatterings revisited in three-flavour resummed chiral perturbation theory

Chiral symmetry breaking may exhibit significantly different patterns in two chiral limits: N_f=2 massless flavours (m_u=m_d=0, m_s physical) and N_f=3 massless flavours (m_u=m_d=m_s=0). Such a difference may arise due to vacuum fluctuations of ss̄ pairs related to the violation of the Zweig rule in the scalar sector, and it could yield numerical competition between contributions counted as leading and next-to-leading order in the chiral expansions of the observables. We recall and extend resummed chiral perturbation theory (ReχPT), a framework that we introduced previously to deal with such instabilities: it requires a more careful definition of the relevant observables and their one-loop chiral expansions. We analyse the amplitudes for low-energy ππ and πK scatterings within ReχPT, which we match in subthreshold regions with dispersive representations obtained from the solutions of the Roy and Roy–Steiner equations. Using a frequentist approach, we constrain the quark mass ratio as well as the quark condensate and the pseudoscalar decay constant in the N_f=3 chiral limit. The results mildly favour significant contributions of vacuum fluctuations suppressing the N_f=3 quark condensate compared to its N_f=2 counterpart.     

e~＋e~－湮没中不同味道夸克喷注带电粒子多重数差别

利用“夸克产生律”与“夸克组合律”计算了ｅ＋ｅ－湮没中重夸克喷注事例的带电粒子多重数，结果与实验符合．并与轻夸克喷注事例及平均夸克味道喷注事例的多重数做了比较．     

Cabibbo current and CP violation in a six quark gauge model

The extended Cabibbo current with CP-violation in a six quark gauge model is obtained in terms of quark mass ratios and phases in the quark mass matrices. The model predicts a long-lived heavy quark and its selection rule.     

Statistical method in quark combination model

We present a new method for solving the probability distribution for baryons,antibaryons,and mesons at the hadronization of the constituent quark and antiquark system.The hadronization is governed by the quark combination rule in the quark combination model developed by the Shandong Group.We employ the method of the generating function to derive the outcome of the quark combination rule,which is significantly simpler and easier to generalize than the original method.Furthermore,we use the formula of the quark combination rule and its generalization to study the property of the multiplicity distribution of net-protons.Taking a naive case of quark number fluctuations and correlations at hadronization,we calculate ratios of multiplicity cumulants of final-state net-protons and discuss the potential applicability of the quark combination model by studying hadronic multiplicity fluctuations and the underlying phase transition property in relativistic heavy-ion collisions.     

Zweig rule violating decays of the new particles

The specific decay modes of the new gy particles and their cascade products are considered according to an approximate scheme of sequential pole dominance proposed by Freund and Nambu, which is dictated by the dual model dynamics. Predictions and comparison with available data are presented. While asymptotically free gauge theory can trace the origin of violation of Zweig rule and the smallness of ψ width, it can only give an estimate of the over-all violation of the rule and is not well suited for each decay channel separately. The sequential pole model fulfils this task.     

Properties of gluon jets

We compute the expected properties of gluon jets in a model based on the KUV jet calculus and recombination. Emphasis is placed on a) the production of baryons, and b) the question of whether hadrons produced by the decays of Zweig rule stable quarkonia (e.g. the upsilon) ine ⁺ e ^? have markedly different energy spectra from those produced by the adjacent quark-antiquark continuum.     

Dynamical violation of the Zweig rule and the energy dependence of π−p→ ϕn

The large magnitude and rapid decrease with energy of σ(π^?p→?n) in the momentum range < 6 GeV/c indicate a dynamical breaking of the Zweig rule. We provide an explicit box diagram amplitude for this process. Zweig's rule is obeyed exactly at all vertices. The size and rapid fall of the cross section are explained in terms of s channel thresholds and duality cancellations in the intermediate states of the box.     

J-dependence of the twist parameter in dual unitarity

It is pointed out that the twist parameter which governs the breaking of exchange degeneracy, Zweig rule violation, exotic exchange, and the relative production of vector and tensor mesons, is J-dependent. A simple model for this dependence reconciles the smallness of exotic exchange with the large ratio of vector to tensor production, and successfully predicts the sign and magnitude of α_?(0)?α_A2(0).     

Photo-absorption sum rules σ<Subscript>–1</Subscript> in different environments (Atoms,nuclei, nucleons)

Combining the spin-dependent dispersion GDH-sum rule, the isotopic-spin-dependent Cabibbo-Radicati sum rule, and the relativistic dipole-moment-fluctuation (i.e. generalized Gottfried) sum rule with the three valence quark configuration of nucleons taken into account for the composition of the ground and the excited states of the nucleon, the relevant moments of the distribution and correlation functions of the quark electric dipole moment operators in the nucleon ground state are expressed via the experimentally measurable nucleon resonance photo-excitation amplitudes.These functions are of interest for checking detailed quark-configuration structure of the nucleon state vector. Within the non-relativistic approach to photo-absorption sum rules for the 3N-nuclei a new σ_–1 sum rule proposed which is based on general charge-symmetry (CS) consequences for the “CS-conjugated” triton and ³He.     

On QCD sum rules of the Laplace transform type and light quark masses

We discuss the relation between the usual dispersion relation sum rules and the Laplace transform type sum rules in QCD. Two specific examples corresponding to the ?-coupling constant sum rule and the light quark masses sum rules are considered. An interpretation, within QCD, of Leutwyler's formula for the current algebra quark masses is also given.     

Quark condensate effects on charmonium-pion scattering

TheJ/ψπ → -DD*,-DD,-D*D* and -DD* cross-sections as a function of √s are evaluated in a QCD sum rule calculation. We study the Borel sum rule for the four point function involving pseudoscalar and vector meson currents, up to dimension four in the operator product expansion. We find that our results are close to those obtained with quark exchange models. We also find that the quark condensate gives the main nonperturbative contribution to the cross-section.     

Low-energy theorems and the Dirac operator spectral density in QCD

We discuss the spectral density of the massless Dirac operator at small eigenvalues and quark masses compatible with the restrictions imposed by the low-energy theorems in QCD. The sum rule for its derivative with respect to the quark mass is found.     

Gluonic corrections to quark vacuum condensate contributions to two-point functions in QCD

We present the α _s corrections to quark vacuum condensate contributions to various types of current correlation functions. Their relevance to the first Weinberg sum rule is discussed. A new derivation of the relation between theA ₁-mass and the ?-mass is presented. The higher order corrections to the socalled non-perturbative quark mass are also discussed.     

Heavy and heavy to light quark expansions

We analyze the phenomenon of heavy quark condensation within the framework of the QCD sum rule approach. We discuss two alternative expansions for massive quark condensates. The first one (heavy to light quark expansion), introduced by Broadhurst and Generalis, establishes a connection between the heavy and light quark worlds. The other one (heavy quark expansion) is valid when only heavy quark systems are considered. As a byproduct we have obtained the coefficients of \(\left\langle {\bar qq} \right\rangle \) , \(\left\langle {\bar qGq} \right\rangle \) , 〈G ²〉 and 〈G ³〉 for all bilinear currents.     

Phenomenology of the proton spin

We analyze the various inputs that go into computing the recently measured first moment of the proton spin structure functiong ₁ ^p (x). The basic inputs are the various valence and sea quark polarisations and the gluonic contribution coming through axial anomaly. We show that the quark model predictions for valence quark polarisations, suitably modified to accommodate Bjorken sum rule, are consistent with measured value of moment of the spin structure function.     

SU(3) analysis of antiproton-proton annihilation into two mesons

We analyse existing data on antiproton-proton annihilation into two mesons using as minimal assumptions charge conjugation invariance, the quark line rule and SU(3). The analysis is greatly facilitated by using a set of invariant SU(3) couplings which is directly related to the contributing quark line diagrams.     

Field theory without asymptotic particles and quarks confinement

The basic idea of a local quantum field theory is presented which should explain the quark confinement, their essentially free behavior under deep-inelastic scattering and at least part of Zweig's rule.