Probability of e+e－ Annihilation in High Energy Collision and Intermittency

Charged particle multiplicity distributions for e⁺e^－ annihilation are shown to be very well described by a negative binomial distribution in high energy collisions.The factorial moments F₂,F₃ and F₄ are given in terms of 3k.     

Measurement of Production Cross Section of Ds+Ds－ in e+e－ Annihilation at the Center-of-Mass Energy of s=4.03GeV

Measurement of the production cross section of the D+s D- s in e+e- annihilation at the Center-of-Mass Energy of s=4.03 GeV is reported in the paper. The cross section for the D+s D- s production has been measured using a data sample of 22.3 pb^－1 collected with BES detector at BEPC e+e- collider. The D+ s measons are reconstructed in the π+,K*0 K+ and K0K+ decay modes. A total number of 94±13 singly tagged D+ s events is obtained from the three modes. This yelds the cross section value σ prod D+s D－ s=(451±63±118)pb for D+ s D－ s production. Based on the numbers of singly tagged D+ s events for each of the three decay modes,the decay branching fractions for D+ s→K *0 K+ and K0K+ have been determined to be (3.02±0.94±0.91)% and (3.28±1.22±0.94)%,respectively.     

Fragmentation Character of Resonance Events in BEPC e+e－ Annihilation

In this paper an important character was found that the final hadron multiplicities of direct J/ψ decays satisfy the same universal mass dependence as that in e⁺e^－→q₀q₀ continuum events. This indicates that the fragmentation of quark and gluon to hadron follows the same mechanism. We give a reasonable interpretation to final baryon multiplicity that is enhanced by 2.5 times in direct Y decays compared to the continuum through our calculating results. But we cannot find this similar phenomenon in direct J/ψ decays.     

Contribution of One-Photon Annihilation at ψ(2S) in e+e－ Experiment

The continuum one-photon annihilation at ψ(2S) in e⁺e^－ experiment is studied. Such contributions to the measured final states ωπ⁰ and π⁺π^－ at ψ(2S) mass are estimated by phenomenological models. It is found that these contributions must be taken into account in the determination of branching ratios of ψ(2S)→ωπ0 and ψ(2S)→π⁺π^－, as well as other electromagnetic decay modes. The study reaches the conclusion that in order to obtain the correct branching ratios on these decay modes at BES, at least 10pb^－1of data below the ψ(2S) peak is needed.     

Study of Colour Connections via Two-Jet Like Events in e+e－ Annihilation

We study the different properties of the two jet like events in e⁺e^－→Z⁰→hadrons under different color connections with the aid of the event generator JETSET. We find that the two kinds of colour connections at the interface of perturbative and nonperturbative QCD, i.e., colour neutral flow and colour separate singlet, lead to significant differences for some observables in the final states. Therefore, the measurements of these observables can be used to distinguish these two kinds of colour connections.     

Hadron Multiplicity Distributions and the Related Parameters in e+e－ Annihilation at Z0 Energy Region

The adaptability of charged hadron multiplicity distributions fitted with negative binomial and its related parameters,forward-backward multiplicity correlation,parameters of clan model,semi-inclusive rapidity distribution and the seagull plots describing the characteristics of transverse momenta of jets are discussed. In particular,the above mentioned parameters in restricted rapidity intervals are analysed and comparde with theoretical results of some phenomenological models of multiparticle production. Most of the results are obtained from 50000 Z⁰ events of ALEPH Collaboration at LEP.     

A Study of the Processes of e+e－→e+e－,μ+μ－ at Large Angle and Measured Luminosities

Using the BES data collected at √S=4.03GeV.the QED processes of e⁺e^－→e⁺e^－,μ⁺μ^－ have been studied. Our measurements agree with the QED prediction,and luminosities obtained from these two final states are compatible at a level of 4%.The total integrated luminosity of 23.1pb^－1 was given for all data collected at this energy region from the calculation.     

Hadrons Production from Light Quark Jets in e＋e－ Annihilation

From calculation and analysis of the mean light flavor quark production probability in light quark jet events, e^＋e^－→q₀q₀→h′s, which involves electromagnetic interaction and hadronic interaction, we determine the dependence of the mean production rates of particles in light (uds) quark jets on the primary quark flavor and number of quark pairs N. Moreover, the relative production rates of leading hadrons are obtained, which shows a strong correlation with the quark pair number N. These results provide a basis for furture studies of particle production in light favor jet at low center-of-mass energy range.     

Angular Asymmetry of Multiplicity in High Energy e+e－ Annihilation to Three Jet Events

A model,which treats three initial parlous as two color singlets and then both of them fragment independently into hadrons, is employed to study the angular dependence of charged multiplicity distribution in e+ e- annihilation into three-jet events at LEP energy region. The calculated results show a distinguished dependence of charged multiplicity to topology structure of events, and also agree well with experiment data from ALEPH collaboration.     

Energy dependence of non-linear dynamical features in e+e－ collisions

A study of the dynamical fluctuation properties at various c.m. energies in e⁺e^－ collisions is performed using the Monte Carlo method. The results suggest that, after the normalized factorial moments of 3-dimensional phase space are analyzed using an isotropical phase space partition, the NFM describing non-linear dynamical properties show a power-law scaling, i.e., the dynamical fluctuations in higher dimensional phase space are isotropic. For c.m. energies √s≤80 GeV, the scaling exponents φ_q increase rapidly with the c.m. energy and for c.m. energies √s>80GeV, the φ_q gradually saturate.     

Strangeness Suppression in e+e－ Light Flavour Jets

From the simple physical picture of quark combination model, we obtain the generate probabilities of various particles and relative ration in e⁺e^－→q₀q₀→h′s process, and find that the relationship between the ration of strange hadron to unstrange hadron γ and the strangeness suppression factor λ. Our results can be used to explain particle ration enhancement observed in experiments without assumption of strangeness suppression factor enhancement.     

Ratio of Baryon to Meson and Baryon Antibaryon Correlation in e+e－ Annihilation under Two Kinds of Color Connections

The ratio of final baryon to meson and baryon antibaryon correlation in e⁺e^－ annihilation are considered as sensitive observables to test the hadronizition models,because among the results obtainted in different popular hadronizition models,only those from JETSET event generator can fit experimental data by adjusting extra ad hoc parameters. We replace the color neutral flow connection,which is the results in large N_c limit and is used in JETSET,with the color separate connection,which is allowed by PQCD,and calculate these observables. We compare the obtained results with those from the standard JETSET7.4 code and the available experimental data. We find that the results and the relevant properties are consistent with data. This shows that the consistency of the data with the results from the standard JETSET7.4 code for these properties does not mean that the traditional color neutral flow is the only color connection selected by NPQCD. The 100% color separate connection is also possible.     

e+e－湮灭中的夸克组合律

本文指出, 夸克组合中快度近关联与QCD的要求一致, 并与慢强子先产生原则一起, 完全确定夸克组合律, 并自动排除重子偶素的产生. 给出了N对夸克随机组成介子、重子与反重子的计算公式. 把它用于e⁺e^－湮灭, 根本不需另引入双夸克对的真空激发等假定, 即自然解释了重子的显著产生.     

Production of charmonium(like) states in e+e－ interactions

We present a search for new charmonium like states in e⁺e^－ annihilation using the initial-state radiation and the process e⁺e^－J/ψD^(*)D^(*). The analyses are based on a huge data sample recorded near the Υ(4s) resonance with the Belle detector at the KEKB e⁺e^－ asymmetric-energy collider.     

THE FRAGMENTATION SCHEMES IN e+e－ ANNIHILATION

The comparison of two fragmentation schemes used in the analysis of e⁺e^－ annihilation are presented in this paper.It is found that the independent fragmentation assumption is strongly disfavored by the data of the final particle multiplicities,and the string fragmentation assumption agrees with experiments.     

QCD JET IN POLARIZED e+e－ ANNIHILATION

Following perturbative QCD theory, the two-jet and three-jet angular distributions in polarized e⁺e^－ annihilation is computed using the dimensional regularization scheme. The azimuthal inhomogeneity caused by the polarization is discussed. We also compute the exact formulae of dependence on ε´,δ to the second order and discuss the correction to G.Sterman and S.Weinberg's result.     

Color Rearrangement in e+e－→W+W－→h's Process

The probability of Color Rearrangement at partonic level in e⁺e^－→W⁺W^－→h,s process is studied using the Color Effective Hamiltonian. The comparison between our results and those of Gutafson and Sjostrand et al. is also given. It is found that this probability cannot be neglected, and it is pointed out that to investigate the Color Rearrangements, the hadronization models should be developped and improved.     

Hadron Multiplicities and Its Momentum Spectra from Color Separate Connection among Final Partons in e+e－ Annihilation Events

We calculate the hadron multiplicities and the momentum spectra of π^±,K^±,p/p in e⁺e^－→q+ng→hadrons for the case where the color separate singlet connections occur among the final partons q+ng with the help of JETSET event generator. We compare the results with those obtainted from the traditional color flow models and the available experimental data. The comparisons show that the momentum spectra obtained in the case of C-weight have a singnificant deviation from the data.,whereas those obtained in the case of T-weight are consistant with the data. The results from the case of T-weight are also consistant with those from the color flow model in most cases,and for proton, are even better than the later as implemented in default JETSET compared with the data.     

Study of the e+ e－ to hadrons via ISR at BABAR

Experimental data from the PEP-II B-factory at 10.6 GeV center-of-mass （c.m.） energy, obtained via initial-state radiation （ISR） with the BABAR detector, are presented. The cross sections for many hadronic processes have been measured from the production threshold to 4-5 GeV of the e^＋e^- c.m. energy. The obtained data allow to study a number of intermediate states and determine the parameters of known resonances and their branching fractions. The exclusive cross section for some number of hadronic sub-processes are presented.     

e+e－湮没过程的多重数分布

本文分析了e⁺e^－ 湮没中多重数的实验分布, 指出可能是夸克数目服从四动量守恒限制下的Poisson分布, 加上组合过程影响的结果. 并利用一种在其他方面取得明显成功的夸克组合律作了计算, 得到与实验符合的结果. 还对轻夸克jet作了单独讨论.