Decay of the J/ψ to Σ0Σ0 Final State

With 7.8 million produced J/ψ events collected by the BES detector at the BEPC, the decay J/ψ→Σ⁰Σ⁰ is analysed. The branching ratio is measured to be BR(J/ψ→Σ⁰Σ⁰)=(0.97±0.04±0.24)×10^－3. The angular distribution is of the form dN dcosθ=N₀(1+α cos²θ) with α value of －0.21±0.27±0.13.     

Determination of the number of J/ψ events with inclusive J/ψ decays

A measurement of the number of J/ψ events collected with the BESⅢ detector in 2009 and 2012 is performed using inclusive decays of the J/ψ. The number of J/ψ events taken in 2009 is recalculated to be(223.7±1.4)×10~6, which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESⅢ software. The number of J/ψ events taken in 2012 is determined to be(1086.9±6.0)×10~6. In total, the number of J/ψ events collected with the BESⅢ detector is measured to be(1310.6±7.0)×106, where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible.     

Determination of the number of J/ψ events with J/ψ → inclusive decays

The number of J/ψ events collected with the BES0 detector at the BEPC/ from June 12 to July 28, 2009 is determined to be (225:3±2:8)×10⁶ using J/ψ → inclusive events, where the uncertainty is the systematic error and the statistical one is negligible.     

Spin-parity analysis of pp¯ mass threshold structure in J/ψ and ψ(3686) radiative decays

A partial wave analysis of the ppˉ mass-threshold enhancement in the reaction J/ψ→γppˉ is used to determine its J(PC) quantum numbers to be 0(-+), its peak mass to be below threshold at M=1832(-5)(+19)(stat)(-17)(+18)(syst)±19(model) MeV/c(2), and its total width to be Γ<76 MeV/c(2) at the 90% C.L. The product of branching ratios is measured to be BR[J/ψ→γX(ppˉ)]BR[X(ppˉ)→ppˉ]=[9.0(-1.1)(+0.4)(stat)(-5.0)(+1.5)(syst)±2.3(model)]×10(-5). A similar analysis performed on ψ(3686)→γppˉ decays shows, for the first time, the presence of a corresponding enhancement with a production rate relative to that for J/ψ decays of R=[5.08(-0.45)(+0.71)(stat)(-3.58)(+0.67)(syst)±0.12(model)]%.     

Scalar gluonium candidates and the radiativeJ/ψ decays

We discuss productions of scalar gluonium candidates in the radiativeJ/ decays. The branching ratios of such productions are estimated on the basis of the Euler-Heisenberg effective Lagrangian for gluon-photon couplings. We mention that these estimates cannot be expected to be accurate to better than within a factor 2. We show that the radiativeJ/ decays probably invalidate gluoniumgg interpretation of the GAMS meson F₀(1590) and a narrow 0⁺⁺ stateS lying below 1 GeV. However, a possible wide scalar effective gluonium candidate(920) is shown not to be excluded by the data on the decayJ/. We also find that the experimental data about radiativeJ/ decays presumably agree with a recently suggested interpretation of F₀(1590) as being approximately a half-and-half mixture of pure 0⁺⁺ gluoniumgg andSU(3)_f singlet quarkoniumq¯q states.     

Production of pseudoscalar glueballs in J/ψ radiative decays

Using a previously developed framework for relativistic bound states we calculate the production of pseudoscalar glueballs in J/ψ radiative decays. The results favour the interpretation of ι(1460) as a fairly pure glueball state. Radiative production of ι(1460) in ϒ and toponium decays should be suppressed.     

Experimental Study of f0 (975) in the J/ψ Decays

Based on 7.8×10⁶ J/ψ events collected by the BES at BEPC, through study of the hadronic decays J/ψ→φπ⁺π^－ and J/ψ→ωπ⁺π^－, the branching ratios of the processes and the mass positions and the widths of f0 are obtained. The angular distributions of J/ψ→φf₀,f₀→π⁺π^－, are fitted and the helicity amplitude ratio of this process is first given.     

Analysis of the B 0(+) → J/ΨD 0(+) decays

We analyze B ⁰⁽⁺⁾ → J/ΨD ⁰⁽⁺⁾ decays by considering the contributions of annihilation diagrams. For each diagram, we calculate the branching ratios for various parameters X _A , which have played a significant role in our results. These parameters have been concluded from the divergence integrals in hard-scattering kernels. Here, we have considered three effective variables, including: Λ(225, 500 MeV), ρ _A (0, 1, 1/2), and φ _A . It is found that the most of the obtained data are placed in the experimental range at Λ = 225 MeV and Λ = 500 MeV for B ⁺ → J/ΨD ⁺ and B ⁰ → J/ΨD ⁰, respectively.     

Study of BESⅢ trigger efficiencies with the 2018 J/ψ data

Using a dedicated data sample taken in 2018 on the J/ψ peak, we perform a detailed study of the trigger efficiencies of the BESⅢ detector. The efficiencies are determined from three representative physics processes,namely Bhabha scattering, dimuon production and generic hadronic events with charged particles. The combined efficiency of all active triggers approaches 100% in most cases, with uncertainties small enough not to affect most physics analyses.     

Σ- atoms and the ΣN interaction

It is shown that among four models of the Nijmegen baryon-baryon interaction only model F --which leads to a repulsive potential felt by the Σ hyperon inside the nucleus-- is consistent both with the analysis of Σ^- atoms and of the (K ^-,π) reactions. The Nijmegen models are used to determine the strong complex single-particle (s.p.) potential of Σ^-, and to calculate the strong-interaction shifts and widths of the lowest observed levels of Σ^- atoms. The results obtained with model F are in best agreement with the experimental data. Received: 15 January 2002 / Accepted: 14 March 2002     

Tuning and Validation of the Lundcharm Model with J/ψ Decays

Using J/ψ decays collected with the BES Ⅲ detector, Lundcharm model parameters are optimized with J/ψlight hadron decays. The dependence of the response function on model parameters is approximated up to the quadratic term, and the model parameters are optimized by simultaneously fitting J/ψ inclusive charged track distributions and event shapes. The Monte Carlo simulations show that optimal parameters yield satisfactory MC distributions as compared to both the J/ψ and ψ（2S） data distributions. These optimal values are suggested for the Lundcharm model to produce J/ψ and ψ（2S） decays to light hadrons.     

Experimental Study of Hadron Inclusive Production in J/ψ Region

The mean multiplicities of mesons π^±、π⁰、K^±、K⁰_s、ρ⁰.K^*0、K^*±、φ and baryons p、Ξ^±、Σ^±(1385) are measured for the first time in J/ψ region with 200,000 J/ψ events collected by the BES detector. The results are compatible with LUND and Shandong phenomenological models. Based on the experimental results, the strangeness suppression factor s/u and spin suppression factor V/(V+P) are calculated to be ～0.3 and ～0.3—0.5 respectively, in good agreement with those given by ARGUS Collaboration in region. This indicates that the SU(6) breaking is consistent in the energy region from J/ψ to .     

Branching fractions of B_((c)) decays involving J/ψ and X(3872)

We study two-body B_((c))→M_c(π,K) and semileptonic B_c→M_cl~-v_1 decays with M_c=(J/φ,X_c~0),where X_c~0=X~0(3872) is regarded as the tetraquark state ccuu(dd).With the decay constant f_x_c~O=(234±52) MeV determined from the data,we predict that B(B~-→X_c~0π~-) =(11.5±5.7)×10~(-6),B(B~C→X_c~0K~0)=(2.1±1.0)×10~(-4),and B(B_s~0→X_c~0K~0)=(11.4±5.6)×10~(-6).With the form factors in QCD models,we calculate that B(B_c~-→X_c~0π~-,X_c~0K~-)=(6.0±2.6)×10~(-5) and(4.7±2.0)×10~(-6),and B(B_c~-→J/φμ~-v_μ~-v_μ,X_c~0μ~-v_μ)=(2.3±0.6)×10~(-2) and(1.35±0.18)×10~(-3),respectively,and extract the ratio of the fragmentation fractions to be f_c/f_u=(6.4±1.9)×10~(-3).     

Study of N*(1440) from J/Ψ decays

For J/Ψ↦ pπ⁰ and pπ⁺π^-, the π⁰ p and pπ⁺π^- systems are limited to be pure isospin-(1/2) due to isospin conservation. This is a big advantage in studying N^* resonances from J/Ψ decays, compared with πN and γN experiments. The process J/Ψ↦ N ^* or p provides a new way to probe the internal structure of the N^* resonances. Here we report a quark model calculation for J/Ψ↦ p, N ^*(1440) and N ^*. The implication for the internal structure of N ^*(1440) is discussed. Received: 1 June 2001 / Accepted: 20 June 2001     

Search for f(J)(2220) in radiative J/ψ decays

We present a search for f(J)(2220) production in radiative J/ψ→γf(J)(2220) decays using 460 fb?1 of data collected with the BABAR detector at the SLAC PEP-II e(+)e? collider. The f(J)(2220) is searched for in the decays to K(+)K? and K(S)?K(S)?. No evidence of this resonance is observed, and 90% confidence level upper limits on the product of the branching fractions for J/ψ→γf(J)(2220) and f(J)(2220)→K(+)K?(K(S)?K(S)?) as a function of spin and helicity are set at the level of 10??, below the central values reported by the Mark III experiment.     

Φπ production in\bar pp annihilation from S and P states and in J/ψ decaysannihilation from S and P states and in J/ψ decays

Recent experiments at LEAR have found surprisingly large branching ratios for reactions $\bar NN \to \phi \pi $ from S-wave initial states while noφπ production is observed from P states of the $\bar pp$ system. Also, noφπ is seen in radiative J/ψ decays even though the rate forωπ is substantial. We calculate theφπ production rates for these three cases viaKK* intermediate states and $K\bar K$ rescattering using the dispersion relation technique; we find that the largeφπ rate in $\bar pp$ annihilations from S states can be reproduced with a reasonable cut-off for the dispersion integral; for J/ψ decays the calculatedφπ rate is compatible with the observed upper limit. We would, however, expectφπ to be seen from $\bar pp$ P-states, in contrast to experimental findings. Yet the branching ratio for $\bar pp \to K*\bar K$ via isospinI = 1 of $\bar pp$ ,¹ P ₁ state is not known; and therefore no definite conclusion can be drawn. We also compare the Dalitz plots we obtain for directφ production and forφ production via rescattering. Clear differences between the two theoretical distributions are observed; yet very high precision data would be required to establish the origin — direct production or rescattering — of theφ mesons. This observation supports the use of the isobar model in data analyses.