APPROXIMATE B.S. WAVE FUNCTIONS FOR AN ELECTROMAGNETIC BOUND SYSTEM OF SPINS (1/2, 1/2) OR (1/2, 1/2) WITH UNEQUAL MASSES

The Bethe-Salpeter equation for an electromagnetic bound system of spins (1/2—1/2) or (1/2—1/2) with unequal masses are solved in this paper. The approximate B.S. wave functions for these systems are given. Utilising these wave functions, the decay rate and branching ratio for Ξ⁰→(Σ⁺μ^－)+v_μ are calculated with accuracy up to order O(α). The results are wΞ⁰→(Σ⁺μ^－)+v_μ1.12(1/sec) and R=[wΞ⁰→(Σ⁺μ^－)+v_μ]/[wΞ⁰→(Σ⁺μ^－)+v_μ]4.7×10^-7. Similarly, the process Λ→(pμ^－)+v_μ is also discussed.     

Measurement of J/ψ decays into ΛΛ π+π-

Based on 58 million J/ψ events collected by the BESⅡ detector at the BEPC, J/ψ→ΛΛ π⁺π^- is observed for the first time. The branching fraction is measured to be Br(J/ψ→ΛΛ π⁺π^-)=(4.30±0.13±0.99)×10^-3, excluding the decays to intermediate states, namely J/ψ→Ξ^-Ξ⁺, J/ψ→Σ(1385)^-Σ(1385)⁺, and J/ψ→Σ(1385)⁺Σ(1385)^-. The branching fractions for these intermediate resonance channels are measured to be:Br(J/ψ→Ξ^-Ξ⁺)=（0.90±0.03±0.18）×10^-3, Br(J/ψ→Σ(1385)^-Σ(1385)⁺)=(1.23±0.07±0.30)×10^-3,and Br(J/ψ→Σ(1385)⁺Σ(1385)^-)=(1.50±0.08±0.38)×10^-3, respectively. The angular distribution is of the form dN/d(cosθ)α(1+αcos²θ) with α=(0.35±0.29±0.06) for J/ψ→Ξ^-Ξ⁺, α=(-0.54±0.22±0.10) for J/ψ→Σ(1385)^-Σ(1385)⁺, and α=(-0.35±0.29±0.06) for J/ψ→Σ(1385)⁺Σ(1385)^-.     

Searches for the technicolor signatures via gg → W±πt± at the Large Hadron Collider

In this paper, we calculate the production of a charged top pion in association with a W boson via gg fusion at CERN's Large Hadron Collider in the context of the topcolor assisted technicolor model. We find that the total cross section of pp → gg → W^±π_t is several dozen femtobarns with reasonable values of the parameters, and the total cross section of pp → W^±π_t can reach a few hundred femtobarns when we consider the sum of the contributions of these two parton subprocesses, gg → W^±π_t and bb → W^±π_t.     

Study of ψ(2S)Decays into pπ and KK

From a study of(2S)decays into vector-pseudoscalar final states,ρπ and KK*,based on a sample of 1.27×10⁶ produced (2S) events,we have set upper limits at 90% confidence level on the branching fractions into ρπof 3.6×10^－5, into K⁺K^*+c.c.of 2.5×10^－5,and into K⁰K^*0+c.c.of 1.2×10^－4.We find that all these decays are substantially suppressed relative to the corresponding J/ψ decays in comparison with PQCD predictions.Our results confirm the MARK Ⅱ measurements at an improved sensitivity level.     

SYMMETRY OF THE ROTATION+VIBRATION SPECTRA FOR NUCLEAR MOLECULE 12C+12C

The rotation-vibration spectra of nuclear molecule ¹²C+¹²C is chassified by the irreducible representations of group U(5). It is shown that the symmetry of rotation-vibration levels of nuclear molecule ¹²C+¹²C are discribed by means of dynamical symmetry U(5)U(4)O(4)O(3).     

First evidence of ψ(2S)→Ω-Ω+

The decay ψ(2S)→Ω^-Ω⁺ is analyzed using 14×10⁶ ψ(2S) events recorded by the Beijing Spectrometer Ⅱ (BESⅡ) at the Beijing Electron Positron Collider (BEPC). Based upon events with no missing charged tracks and a satisfactory four-constraint kinematic t, we determine the upper limit for the branching fraction of ψ(2S)→Ω^-Ω⁺ to be 1.5×10⁴ at a 90% confidence level. By including events with one missing charged track, we are able to report the first evidence of an Ω⁺ signal with a statistical signi cance of 3.1|σ. The branching fraction of ψ(2S)Ω⁺ is determined to be (4.80±1.56(stat)±1.30(sys))10⁵.     

Branching ratio and CP asymmetry of Bs→K0*(1430)η(') decays in the PQCD approach

In the two-quark model supposition for K₀^*(1430), which can be viewed as either the first excited state (Scenario Ⅰ) or the lowest lying state (Scenario Ⅱ), the branching ratios and the direct CP-violating asymmetries for decays B_s⁰→K₀^*0(1430)η^(') are studied by employing the perturbative QCD factorization approach. We find the following results: (a) The CP averaged branching ratios of B_s⁰→K₀^*0(1430)η and B_s⁰→K₀^*0(1430)η' are small and both in the order of 10^-7. If one views K₀^*(1430) as the lowest lying state, B (B_s⁰→K₀^*0(1430)η)≈3.9×10^-7 and B (B_s⁰→K₀^*0(1430)η')≈7.8×10^-7. (b) While the direct CP-violating asymmetries of these two decays are not small: if we still take the parameters of K₀^*(1430) in scenario Ⅱ, A_CP^dir (B_s⁰→K₀^*0(1430)η)≈56.2% and A_CP^dir (B_s⁰→K₀^*0(1430)η')≈2.4%. (c) The annihilation contributions will play an important role in accounting for future data, because both the branching ratios and the direct CP asymmetries of these two decays are sensitive to the annihilation type contributions.     

(EC/β+) Decay of 130Nd and 140Tb

Isotopes,¹³⁰Nd and ¹⁴⁰Tb were produced using enriched targets ⁹⁶Ru and ¹⁰⁶Cd, respectively,bombarded by ³⁶Ar ion beam. The two nuclides were identified and studied by a He-jet tape transport system in combination with "X-γ" and "γ-γ" coincidence measure- ments. The half-life of ¹³⁰Nd was determined to be (13±2)s. The EC/β⁺ decay scheme of 130Nd was proposed for the first time, and the spins and parties of the ground-state and observed low-lying states in the daughter nucleus ¹³⁰Pr were speculated tentatively. The previous simple EC/β⁺ decay scheme of ¹⁴⁰Tb was revised, and the spin-parity of its groundstate was assigned to be 7⁺.     

THE BEHAVIOURS OF F2ep(X,Q2)-F2en(X,Q2) AND THE SCALE-BREAKING PARAMETER

The scale-breaking parameter F₂^ep(x, Q²) of non-singlet component F₂^ep-F₂^en and some other quantities in the electro-production process are discussed by usinb the analytic expression for the distribution function of valence quarks in ha.drons up to leading log approximation given by a, previous paper^[1]. Comparisons with data are also given.

     

Development of Yangbajing air shower core detector for a new EAS hybrid experiment

Aiming at the observation of cosmic-ray chemical composition in the "knee" energy region, we have been developing a new type of air-shower core detector(YAC, Yangbajing Air shower Core detector array) to be set up at Yangbajing(90.522?E, 30.102?N, 4300 m above sea level, atmospheric depth: 606 g/m2) in Tibet, China.YAC works together with the Tibet air-shower array(Tibet-Ⅲ) and an underground water Cherenkov muon detector array(MD) as a hybrid experiment.Each YAC detector unit consists of lead plates of 3.5 cm thickness and a scintillation counter which detects the burst size induced by high energy particles in the air-shower cores.The burst size can be measured from 1 MIP(Minimum Ionization Particle) to 106 MIPs.The first phase of this experiment, named"YAC-Ⅱ ", consists of 16 YAC detectors each with a size of 40 cm×50 cm and distributed in a grid with an effective area of 10 m2.YAC-Ⅱ is used to check hadronic interaction models.The second phase of the experiment, called"YAC-Ⅱ ", consists of 124 YAC detectors with coverage of about 500 m2.The inner 100 detectors of 80 cm×50 cm each are deployed in a 10×10 matrix with a 1.9 m separation; the outer 24 detectors of 100 cm×50 cm each are distributed around these to reject non-core events whose shower cores are far from the YAC-Ⅱ array.YAC-Ⅱ is used to study the primary cosmic-ray composition, in particular, to obtain the energy spectra of protons, helium and iron nuclei between 5×1013eV and 1016 eV, covering the "knee" and also connected with direct observations at energies around 100 TeV.We present the design and performance of YAC-Ⅱ in this paper.     

Structure Properties of Light Nuclei(Ⅰ)Structure of Li Isotopes

The structure properties of Li isotopes are investigated in the framework of large-basis shell model.0hω calculation can reproduce the structure of ^6,7Li, but for some states of ^8,9 Li far from β-stability line the effect of(0+2)hω excitation should be taken into account for reproducing the experiment at data.For drip line nuclei,enlarging model space or changing the interaction can not reproduce the exotic properties of nucleus ¹¹Li.The exotic properties of some states of nuclei ^6—8Li are also briefly discussed.     

"ONE,TWO, INFINITY" MODEL FOR PRECOMPOUND REACTION AND NUCLEAR SIZE EFFECT

The influence of limited nuclear size effect to "One, two, infinity" model for precompound reactions is discussed. The inclusive proton spectra in ⁵⁸Ni, ⁹⁰Zr, ²⁷Al(p,p') reactions and the inclusive neutron spectra from ²⁷Al(p,n) reaction at 90 MeV are calculated. The results are in a good agreement with the data.     

CALCULATION OF THE ELASTIC-SCATTERING CROSS-SECTION OF ENERGETIC ELECTRON BY 40Ca NUCLEUS IN CONSIDERATION OF THE INFLUENCE OF“PION CONDENSATION”

Using Migdal's theoretical results of "pion Condensation", the influence of "π condensation" on the distribution of charge of N=Z nucleus is determined. The elastic-scattering differential cross-section of energetic electron by ⁴⁰Ca nucleus is also calculated. The results of our calculations agree better with the experimental data.     

THE BEAM ENVELOP ANALYSIS FOR NONPERIODIC SYSTEMS

The beam envelops for non-periodic alternating gradient focusing system is analysed. The accurate analytic expressions of the beam envelop function β is obtained by solving the following non-linear differential equation:(√β)^н+Q(Z)√β-1/(√β)³=0,
The conditions of existing the maximum and the minimum of beam envelop are discussed. And we have derived the accurate formulae with which one can calculate the maximum and the minimum values of envelop and their position. The method developed in this paper is different from the convintional matrix computational method. Both methods can be checked by each other.     

QCD Sum Rules for the 0++ Three-Gluon Scalar Glueball

The two-point function of the 0⁺⁺ three-gluon scalar current is calculated by including not only the perturbative contribution but also the non-perturbative contributions of condensates of dimension up to six The QCD sum rules for the 0⁺⁺ three-gluon scalar glueball are deduced in the "zero-width resonance plus continuum" model. The mass of this glueball is determined to be 1.45GeV approximately.     

The Production of Bc(Bc) Meson Through Z0 Boson Decay

Based on the most important "hard" production mechanism,the production rate of B_c(or B_c) meson being accompanied with one c(or c) and one b(or b) heavy quark jets through Z⁰ decay is computed in this paper.It is pointed out that at LEP up to next run,quite a lot of events with one B_c or B_c meson may be obtained,so that it becomes accessible to study the properties of B_c and B_c mesons throngh Z⁰ decay experimentally.     

TESTING GLUON DISTRIBUTION FUNCTION OF HADRONS IN LARGE PT PROCESS WITH DIRECT PHOTON EMISSION

In this paper we disscuse disscuse the physicsical aspect of cross-section differences Δ_AB^cγ=dσ(AB→cγX)-dσ(AB→cγX) and give the simple rules to select the elementary subprocesses which contribute to cross-section differences.
We bind a way to test the gluon distribution functions of hadrons through the measurement of cross-section difference or combination of cross-section differences in the large P_T process with direct photon emission. Moreover we obtain simple relations between each combination of cross-sections and the corresponding gluon distribution functions of proton, neutron, pion and daon:
G_p⁸(x)/(Δ_pp^hγ－Δ_pp^hγ)=G_n⁸(x)/(Δ_pp^hγ)=G_π⁸(x)/(Δ_π+p^hγ+Δ_π－p^hγ=G_K⁸(x)/(Δ_K+p^hγ+Δ_K－p^hγ)which are expected to be test in experiment.     

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.     

Krein regularization of λφ~3 theory

In this paper, the one-loop self energy of λφ3 theory is calculated by using Krein regularization in four and six dimensions and the result, which is finite, is compared with the conventional result of λφ3 theory in Hilbert space. The self energy is calculated in the one-loop approximation and the result is automatically regularized as a result of "Krein Regularization".