1992 Vol. 16, No. 9
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The Beijing Spectrometer (BES),as a general purpose magnetic spectrometer working at the Beijing Electron Positron Collider (BEPC).consists of several subdetectors.It is used for reconstruction of the exculusive final states from e+e－ interaction and study of the charm physics and τ lepton physics.It has solid angle coverage,excellent charged particle identification and momentum resolution,and high detection efficiency of low energy photons.The constitution and performances are given in detail.
The generalized coagulation equations with fragmentation mechanism as a geodesic equation for motion of a representative point were formulated in an infinite-dimensional space endowed with an affine connection by a geometrical approach.
The strong CP violation,the PQ mechanism and the axions in the standard model are discussed.The model of techniaxion is established.The mass and the lifetime of techniaxion,the coupling for techniaxion with other matters are obtained.The constraints on the properties of techniaxion from astrophysical and cosmological considerations are discussed.An axion physical state should exist in the cosmic rays.
Based on the Beckmann method,a new quantitative method for the study of multi-particle azimuthal correlations is proposed.Collisions of 1.2A GeV Ar+KC1 in the LBL streamer chamber are analyzed with this new method and the original Beckmenn method,respectively.The experimental results have been compared with the Vlasov-Uehling-Uhlenbeck model predictions for different nuclear equations of state.Using the new method,the incompressibility of nuclear matter can be estimated.
In this paper the structure of the wide resonance θ(1720) produced in J/ψ radiative decay is studied by using moment analysis.Since the f'2(1525) and θ(1720) resonances overlap in this mass region,two three-states coupling structure modes 2++(f'2(1525))+0+++0++ and 2++(f'2(1525))+0+++2++ are discussed.It is helpful to make clear the structure of the wide resonance θ(1720),de-termine masses、widths、spins and other important properties of the two resonance states,for example G(1590) and f2(1720),including therein and understand the two interesting states better.
It is proposed that the average radius of the Source obtained from twopion interferometry analyses is a suitable quantity to describe the spatial size of the source by comparing the correlation functions from different source density destributions directly.When comparing the source spatial parameters from different correlation functions,the average radius of the source is a superior standard parameter to the root-mean-square radius suggested by Bartke and Kowalski,and is superior to the factor suggested by Goldhaber et al.A systematic study of the results from different heavy ion experiments demonstrates that a more reasonable result can be obtained by utilizing the average radius as a standard for comparison.
The α-particle structure models for 12C and 16O are tested by means of proton total cross sections and forward scattering amplitudes in the intermediate energy range.The total cross section for 4He is discussed.The results provide a support to the α-particle models of 12C and 16O.
Fission cross sections and angular distributions have been measured for the 16O+238U reaction at bombarding energies from 73.7 to 93.7 MeV.The fission excitation function is well reproduced on the basis of Wong model.The fission-fragment angular distributions are calculated in terms of the transition-state theory,with the transmission coefficents extracted from the excitation function calculation.It is found that a discrepancy between the observations and the predictions in angular anisotropy of fission fragments exists at near-and sub-barrier energies.Moreover the tendency of the anistropies as a function of the center-of-mass energy aren't the same as previous measurement results.
In this paper,the irreducible representations and Wigner coefficients of SLq(3) have been obtained.The generators of SLq(3) satisfying the serre relations are considered as 1/2 rank tensor——like of SLq(2).Their reduced matrix elements can be calculated by a set of recurrent formula.The isoscalar factors (ISF) of SLq(3) can also be derived by them.This means that the Racah Factorization Lemma is also exact for the quantum algebra SLq(3).
By means of introducing a nonlinear transformation,the n-body correlation Green's functions G(n),c are separated out from the n-body Green's functions G(n) A set of non-relativistic dynamic equations for the time evolution of G(n),c is derived which provides a complete,systematic and non-perturbative approach for describing quantum many-body systems.
The dynamical aspects of IBM-Ⅱ in the continuous variables representation are investigated by using the Dynamical Group Representation-Generator.Coordinate Method.The transformation from the degrees of freedom of proton and neutron to those of on-phase and out-of-phase motions is introduced and effective Hamiltonian with this mode is derived.The features of the Hamiltonian.especially the minimum point of the system,are discussed.
The extended Thomas-Fermi Approximation (ETF) is applied to study the microscopic foundation of the continuous medium model of the nucleus and macroscopic model based on nucleon-nucleon interaction is obtained.With Skyrme forces,it has been studied that the model reproduces the results of ETF calculations quite well.
In this paper we investigate the polarization structure of the process J/ψ→ωf2(1270) and f2(1270)→ππ by using the generalized moment analysis method and give some relations of moments to represent four helicity amplitude ratios of the process.
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