Chiral Lagrangian Treatment of 0^＋＋ Mesons and 0^＋＋ Glueballs

Within the framework of a nonlinear chiral Lagrangian the mass spectra and the decay properties of 0^＋＋ states below 2 GeV are studied. Assuming that f0（980）, a0（980）, K0（1430）, and f0（1500） comprise an SU（3） nonet, we make a detailed prediction about the static properties of the 0^＋＋ mesons. The substructure analysis of these states in terms of two- and four-quark components as well as a glueball component is carried out. We also consider the interaction Lagrangian and provide a preliminary study of the strong and radiative decays of the 0＋＋ mesons. The scalar glueball masses and partial widths are also presented. In view of the fact that few data of 0＋＋ mesons are clearly given in the present PDG （Particle Data Group） list and that the four-quark content of mesons is a hot issue both experimentally and theoretically, the predicted results of the paper may be helpful for upcoming experimental and theoretical studies of these mesons.     

ψ″ Decays to charmless final states

The importance of measuring the decays of the ψ″ = ψ (3770) resonance is discussed. These decays can shed light on a possible discrepancy between the total and cross-sections at the ψ″, and on a proposed mechanism for enhancement of penguin amplitudes in B meson decays through charm-anticharm annihilation. Measurements (including the ψ″ line shape) in states of definite G-parity and in inclusive charmless final states such as η′ + X are found to be particularly important.     

Is chiral symmetry restored in the excited meson spectrum?

The large degeneracy observed in the excited meson spectrum by the Cristal Barrel Collaboration in the experimental data on proton–antiproton annihilation in flight into mesons in the range 1.9–2.4 GeV has been interpreted as a signal of chiral symmetry restoration. In this work we suggest that such degeneracy may be an indication of the confinement potential modification by color screening. The experimental data can be fairly well reproduced in a constituent quark model with a screened linear confinement potential without changing the dynamical quark mass. Observables that could discriminate our model from those which explicitly restore the chiral symmetry are proposed.     

Determination of J/φ Event Number via J/φ→μ+μ- and J/φ→ e+e- at BESIII

The decays of J/φ→μ⁺μ^- and J/φ→ e⁺e^- are studied by Monte-Carlo simulation, based on the Beijing Spectrometer (BES)Ⅲ offline software system. The methods of determination of the J/φ event number via J/φ→μ⁺μ^- and J/φ→ e⁺e^- are presented, respectively. These methods can be used to determine the J/φevent number for the coming BESⅢ J/φ data sample.     

Chiral Suppression and SU（3） Symmetry in Scalar Glueball Decays

We theoretically evaluate the decay rates of a scalar glueball up to the order O（αs）, where only two Feynman diagrams contribute and a special attention is paid on possible flavour SU（3） symmetry breaking in the process. It is concluded that the SU（3） flavour symmetry may be respected in any case. However, due to chiral suppression in Go →qq, F（Go →qq qq） very likely is larger than F（Go→qq）. These results are supported by the experimental data on the decays of xco（1P） （0^＋＋）. Based on this result, we propose a criterion to identify the scalar glueball.     

J/ψ Inclusive Photon Spectrum at BESIII

With a 15M J/ψ inclusive Monte Carlo sample, the absolute branching fraction of J/ψ→γ\η' from the J/ψ inclusive photon spectrum is measured to be Br(J/ψ→γ\η')=(4.68±0.08±0.27)×10^-3, which is in good agreement with the input value. The J/ψ→γf_J(2220) is also searched for using the same sample. Under our assumptions, the statistical significances of J/ψ→γf_J(2220) are larger than 7\σ.     

Monte Carlo Simulation on Glueball Search at BESIII

The J/ψ radiative decays are suggested as promising modes for glueball search. A full Monte Carlo simulation of J/ψ →γηη and γηη, based on the design of BESIII detector, is performed to study the sensitivity of searching for a possible tensor glueball at BESIII.     

Masses of light tetraquarks and scalar mesons in the relativistic quark model

Masses of the ground-state light tetraquarks are dynamically calculated in the framework of the relativistic diquark–antidiquark picture. The internal structure of the diquark is taken into account by calculating the form factor of the diquark–gluon interaction in terms of the overlap integral of the diquark wave functions. It is found that scalar mesons with masses below 1 GeV, f ₀(600) (σ), K ₀^*(800) (κ), f ₀(980) and a ₀(980), agree well with the light-tetraquark interpretation.     

Comparative Regge analysis of Λ,ΣΛ(1520) and Θ<Superscript>+</Superscript> production in γp,πp and pp reactions

Using the Quark-Gluon Strings Model --combined with Regge phenomenology-- we perform a comparative analysis of Λ, Σ⁰, Λ(1520) and Θ⁺ production in binary reactions induced by photon, pion and proton beams on the nucleon. We find that the existing experimental data on the γp↦K⁺Λ differential and total cross-sections can be described very well by the model for photon energies 1-16 GeV and - t < 2 GeV² assuming a dominant contribution of the K^* Regge trajectory. Moreover, using the same parameters we also reproduce the total γp↦K⁺Σ⁰ and γp↦K⁺Λ(1520) cross-sections suggesting a “universality” of the Regge model. In order to check the consistency of the approach we evaluate the differential and total cross-sections for the reaction π^-p↦K⁰Λ which is also found to be dominated by the K^* Regge trajectory. Using the apparent “universality” of the Regge model we extend our scheme to the analysis of the binary reactions γp↦¯⁰Θ⁺, π^-p↦K^-Θ⁺ and pp↦Σ⁺Θ⁺ as well as the exclusive and inclusive Θ⁺ production in the reactions pp↦p¯⁰Θ⁺ and pp↦Θ⁺X. Our detailed studies demonstrate that Θ⁺ production does not follow the “universality” principle, thus suggesting an essentially different internal structure of the exotic baryon relative to conventional hyperons or hyperon resonances.     

Retardation effects in the rotating string model

A new method to study the retardation effects in mesons is presented. It is based on a generalized rotating string model, in which a nonzero value of the relative time between the quark and the antiquark is allowed. This approach leads to a retardation term in the Hamiltonian which behaves as a perturbation of the nonretarded Hamiltonian and preserves the Regge trajectories for light mesons. The straight-line ansatz is used to describe the string, and the relevance of this approximation is tested. It is shown that the string is actually curved because of retardation, but this bending does not bring a relevant contribution to the energy spectrum of the model.     

Isospin breaking in the pion–nucleon scattering lengths

We analyze isospin breaking through quark mass differences and virtual photons in the pion–nucleon scattering lengths in all physical channels in the framework of covariant baryon chiral perturbation theory.     

Systematic study on QCD interactions of heavy mesons with ρ meson

The strong interactions of the negative-parity heavy mesons with ρ   meson may be described consistently in the context of an effective Lagrangian, which is invariant under isospin SU(2)$\mathit{SU}(2)$ transformation. Four coupling constants g_HHρ$g_{HH\rho }$, f_H∗Hρ$f_{H^{\ast }H\rho }$, g_H∗H∗ρ$g_{H^{\ast }{H}^{\ast }\rho }$ and f_H∗H∗ρ$f_{H^{\ast }{H}^{\ast }\rho }$ enter the effective Lagrangian, where H  (H^∗)$(H^{\ast })$ denotes a pseudoscalar bottom or charm meson (the corresponding vector meson). Using QCD light cone sum rule (LCSR) method and, as inputs, the hadronic parameters updated recently, we give an estimate of g_H∗H∗ρ$g_{H^{\ast }{H}^{\ast }\rho }$ and f_H∗H∗ρ$f_{H^{\ast }{H}^{\ast }\rho }$, about which little was known before, and present an improved result for g_HHρ$g_{HH\rho }$ and f_H∗Hρ$f_{H^{\ast }H\rho }$. Also, we examine the heavy quark asymptotic behavior of these nonperturbative quantities and assess the two low energy parameters β and λ of the corresponding effective chiral Lagrangian.     

String deformations induced by retardation effects in mesons

The rotating-string model is an effective model of mesons, in which the quark and the antiquark are linked by a straight string. We previously developed a method to estimate the retardation effects in this model, but the string was still kept straight. We now go a step further and show that this kind of retardation effects cause a small deviation of the string from the straight line. We first give general arguments constraining the string shape. Then, we find analytical and numerical solutions for the string deformation induced by retardation effects. We finally discuss the influence of the curved string on the energy spectrum of the model.     

Qq^- Q ^- q＇ States in Chiral SU（3） Quark Model

We study the masses of Qq^- Q ^- q＇ states with J^PC=0^＋＋,1＋＋ and 2^＋＋ in the chiral SU（3）quark model, where Q is the heavy quark （c or b） and q （q＇） is the light quark （u, d or s）. According to our numerical results, it is improbable to make the interpretation of [cn^-C^-n]1＋＋ and [cn^-C^-n]2＋＋ （n = u, d） states as X（3872） and Y（3940）, respectively. However, it is interesting to find the tetraquarks in the bq^-b^-q＇ system.     

Excited heavy tetraquarks with hidden charm

The masses of the excited heavy tetraquarks with hidden charm are calculated within the relativistic diquark–antidiquark picture. The dynamics of the light quark in a heavy–light diquark is treated completely relativistically. The diquark structure is taken into account by calculating the diquark–gluon form factor. New experimental data on charmonium-like states above open charm threshold are discussed. The obtained results indicate that X(3872), Y(4260), Y(4360), Z(4248), Z(4433) and Y(4660) could be tetraquark states with hidden charm.     

Addendum and Corrigendum： ＂Heavy Quarkonium Spectra in a Quark Potential Model＂

In a paper published years ago by me and my collaborators, the properties of heavy quarkonium systems were studied based on the Dick potential, which explicitly included the color factor in the potential and the non-relativistic SchrSedinger equation was numerically solved. However, another paper by Barakat and Chaba appeared online a few months earlier, which dealt with a similar problem, but used the shifted-expansion technique （SLET） to solve the semi-relativistic wave equation for the Dick potential up to a QCD color factor. Since both the papers solved the same Dick potential model, similar energy spectra due to the small relativistic effect were obtained for this heavy quark system. I and my collaborators did not point out this similarity in Ref. This should be added to give credit to Ref.