1995 Vol. 19, No. 2

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Precise Measurement of τ Mass
BES Collaboration
1995, 19(2): 97-105.
Pairs of τ lepton produced near the threshould have been studied in eμ,ee,eπ,μμ,μπ,ππ final states with the data taken by BES detector at BEPC collider in 1992.The obtained τ mass is MeV by fitting data with likelihood method.
Identification of Excited States in 117Xe
Liu Zhong, Sun Xiangfu, Zhou Xiaohong, Lei Xiangguo, Jin Hanjuan, Guo Yingxiang, Pan Qiangyan, Zhang Yuhu, Chen Xinfeng, Luo Yixiao, Wen Shuxian, Yuan Guanjun, Li Guangsheng, Yang Chunxiang
1995, 19(2): 106-109.
Excited states of 117Xe were populated via the reaction 92Mo(28Si,2pn)at 115MeV.The emitted promt γ-rays were measured by using in beam γ-ray experimental techniques.Five bands in 117Xe have been identified,two of them are observed for the first time,and the three known bands are extended to higher spins.
Atmospheric Cherenkov Images of Cosmic Ray Muons
Jiang Yinlin
1995, 19(2): 110-115.
The theoretical results of the atmospheric Cherenkov images of a muon on the focal plane of a reflector are given under the ideal conditions.The use to calibrate secondgeneration atmospheric Cherenkov imaging telescope is introduced briefly.
Study of Avalanche of Gas Detector
Xu Changbu, Xu Tong, Xu Zizong
1995, 19(2): 116-122.
Based on Towsend's avalanche mode and some basic physical ideas,a unified formula for gas amplification working under proportional mode and limited proportional mode is deduced.This formula explains the experimental data well.By fitting the data, some important parameters are displayed.The effective capacitor describes the effect of space charges,and the linearity shows the state of the gas detector(under PM or LPM).This formula also gives some explanations on SQS mode while space charges are one of the important factors effecting the avalanche.
The Integrability Condition of Three-Dimensional Exactly Solvable Model-Baxter-Bazhanov Model in Statistical Mechanics
Hu Zhanning, Hou Boyu
1995, 19(2): 123-130.
From the chiral Potts model the"inversion"and"star-square"relations of the Baxter-Bazhanov model are obtained.This means that the tetrahedron equation which is a commutativity condition for the three-dimensional cubic lattice is a consequence of the star-triangle relation of the chiral Potts model.The additional constraints in tetrahedron equation hold naturally when the Boltzmann weights are parametrized in terms of the Zamolodchikov angle variables.It is point out that the star-triangle relation of the three-dimensional model can be gotten by using the method given in this paper,which includes the result of Baxter and Bazhanov's.
Top-loop Correction to TC Neutral PG Boson Anomaly Coupling
Yue Chongxing, Lu Gongru
1995, 19(2): 131-136.
The total effective lagrangian of the gauge boson couplings to the neutral PG(Psudo-Goldstone)boson in technicolor models is developed.The effect of t-quark loop on the anomaly coupling is computed.Such effect significantly changes the coupling strength.The result is in favor of the detection of the neutral PG bosons.
Analytical Calculation of the Fixed Length Lattice SU(2)-Higgs Model
Zheng Xite, Chen Hong, Lu Zao, He Yuan
1995, 19(2): 137-142.
The phase diagram of the lattice system of the SU(2) gauge field coupled with the fixed length Higgs field in the fundamental representation has been calculated analytically to the fourth order of the cumulant expansion.The variational parameters have been determined by the scanning method.The obtained phase diagram is in fine agreement with the Monte Carlo result.The calculation also has been made for the Polyakov lineof the SU(2)-Higgs and the pure SU(2) models at finite temperature(Nτ=1).The best up to now approximate analytical result βc for the pure SU(2) model is obtained.
The Analytical Approach for the Two-dimensional O(3) Non-linear σ Model
Zhao Peiying
1995, 19(2): 143-147.
In the lattice gauge theory,by using the variational cumulant expansion,we calculate the internal energy and specific heat for the two-dimensional O(3) non-linear σ model.A comparison with Monte Carlo data is also presented.
Multiparticle Bose Correlations: Probes for Granular Source of Quark-Glunon-Plasma Droplets
Zhang Weining, Liu Yiming, Huo Lei, Jiang Yuzhen
1995, 19(2): 148-155.
The multiparticle Bose correlations of bosons emitted from dispersed thermal droplets of quark-gluon plasma are simulated by Monte Carlo.Multiparticle Bose correlations can offer more sensitivity to probe the granularity of the Bosonemitting source than two-particle Bose correlations.A promising signal of the existence of a mixed phase of quark-gluon plasma and hadronic gas can be obtained from multiparticle observables.
Studying the influences of Mean Field and NN Cross Section on the Collective Flow at High and Intermediate Energy in the Relativistic VUU Approach
Zhou Hongbo, Li Zhuxia, Zhuo Yizhong
1995, 19(2): 156-164.
We have studied the collective flow at high and intermediate energy in a relativistic Vlasov-Uehling-Uhlenbeck(RVUU)approach based on Walecka's QHD-I model,with the aim of probing the nuclear matter equation of state(EOS)and the in-medium n-n cross section.
Suppression of Dilepton Production in Expanding Hot Baryon-Rich Quark-Gloun Matter
He Zejun, Zhang Jiaju, Qiu Xijun
1995, 19(2): 165-171.
With the increase of the initial baryon density, the dilepton production in invariant masses between 2mπ and 1GeV is shown to be suppressed and an abnormal peak of the dilepton spectrum appears near the invariant mass0.75GeV if the baryonrich quark-gluon matter has been created in relativistic nucleus-nucleus collisions.These predictions are important for several large-scale experiments at CERN and Brookhaven.
Strong Stopping of Nuclear System at AGS Energy
Song Guang, Sa Benhao, Wang Zhongqi, Lu Zhongdao, Zhang Xiaoze, Zheng Yuming
1995, 19(2): 172-177.
A simple relativistic hadronic cascade model is given and then applied to simulate the reaction of Si(14.6AGeV/c)+Au.The △ resonance effects on the rapidity distributions of proton and pion and on the transverse mass distribution of proton are investigared.In this model,the longitudinal momentum of scattered particle is given by stopping law while the transverse momentum is sampled from exponential or Guassian distribution.The theoretical results are in a good agreement with the E802 new results and with the E810(E814)data.This indicates that that introduction of △ resonance is necessary for the better description of the reaction process.It is also convinced that the strong nuclear stopping at AGS energy is no doubt any more.
Effect of Negative Energy Component on Baryon Spectra
Dong Yubing
1995, 19(2): 178-184.
Employing instantaneous Bethe-Salpeter equation and taking into account the correction of negative energy component of Dirac spinor to one-gluon exchange interaction,the calculation of the △,N baryon spectra is carriedout.We find that the effect changes the potential parameters significantly,but leaves the global structurs of spectrum almost untouched.
Electric Dipole Moments of Actinide Region
Shi Zongren, Wan Shuying
1995, 19(2): 185-192.
Theoretically and experimentally,the relation between electric dipole moment D and rotation angular momentum I is linear approximately.It shows the effects to D from Coriolis and centrifugal force.Therefore,the experimental ground state electric dipole moment D0 exp of 31 actnide nuclei have be obtained and compared with the theoretical D0 calculated by macro-micro method,mean-field theory and αmolecular dipole cluster model.