1993 Vol. 17, No. 1

Display Method:          |     

Forward-Backward Multiplicity Correlations in pp Collisions at 400GeV/c
WANG Shao-Shun, ZHANG Jie, YE Yun-Xiu, XIAO Chen-Guo, LUO Qi, CHENG Zheng-Dong, ZHANG Xue-Qian, XU Wan-Li, WIONG Wei-Jun
1993, 17(1): 1-7.
The pseudo-rapidity distributions of charged particles produced in pp collisions at 400GeV/c have been measured using LEBC films.The multiplicity distributions in forward hemis-phere at fixed total multiplicities are obtained.The forward-backward multiplicity correlation strength in full phase spsce,central region and off-central region of the pseudo-rapidity distribution are calculated.
The figures of the correlation strength versus pseudo-rapidity windows are obtained.The experimental data of the forward-backward correlation have been analyzed with cluster model.The results show that the average cluster size is dependent on whether the leading-particle effect is taken into account.
Another Possible Interpretation of SQS Mechanism
LI Huan-Tie
1993, 17(1): 8-16.
Experiments on self quenching streamer discharge in cylindrical tube and wire chamber are performed,and an interpretation of SQS mechanism is proposed in this paper.The excited atoms or molecules created in the latent track and subsequent avalanche play an important role,they form the main photo-electron source and the interaction between them is also possibly a source of ionizing photon.A formula that describe the jump and streamer charge is deduced.The effect of electric field of the space charge is computed.The comparison between theory and experiments is made.
Ward-Takahashi Identities and Mass Spectra in (2+1) Dimensional SU(2) Four-fermi Model
SHEN Kun, QIU Zhong-Ping
1993, 17(1): 17-27.
Ward-Takahashi identities with composite fields are utilized to inverstigate (2+1) dimensional model with SU(2) four-fermion couplings.When SU(2) chiral symmetry is both explicitly and dynamically broken,fermion mass is dynamically generated and mass spectra of the bound states are obtained The properties of vector and axial-vector currents are discussed.It turns out that the bound state πα acquires a mass and the axial-vector current is partially conserved,and the Goldberger-Treimab relation is approximately valid in the case of small fermion current masses.
Conformally Reduced WZNW Theory,New Extended Chiral Algebras and Their Associated Toda Type Integrable Systems (Ⅰ) General Framework
1993, 17(1): 28-37.
We propose and analyse a large class of conformal reductions Cons [g(H,d)] of WZNW theory based on the integral gradations of the underlying Lie algebra g.The W-bases of the associated W-algebras W[g(H,d)] are constru ted under the generalized Drinfeld-Sokolov gauge which we call O'Raifeartaigh gauge of the constrained Kac-Moody currents,and the equations of motion of the extended Toda type integrable systems corresponding to these Walgebras are derived also.
The Influence on the Baryon and Its Resonances From a New Additional Mass Term in the Skyrme Model
1993, 17(1): 38-43.
This paper studied the influence on the baryon and its resonances from a new additional mass term which is derived by the Skyrme Lagr ngian after quantum mechanical treatment.
The Mass Effects of Gluino and Squark On Z Decay Into bb
HU Bing-Quan, LI Chong-Sheng, CHEN Xin-Yong, WEI Yan-Shen
1993, 17(1): 44-48.
We studied the one-loop gluino correction to the process Z→bb in the minimal supersymmetric standard model (N=1) and investigated the dependence of the process on gluino and squark masses and the effects of L-R Squark mixing.For some values of the massesunder study,the correction to the ratio of the Z→bb partial width to all hadrons' may reach 3%.
Multi-Pion Correlations in Two-Pion Interferometry
ZHANG Wei-Ning, JIANG Yu-Zhen, WANG Shan, LIU Yi-Ming
1993, 17(1): 49-56.
The influence of multi-pion correlations on two-pion interferometry analysis in multi-pion events can be expressed as the ratio of a multi pion correlation factor for the sample of like-pion pairs to a residual correlation factor for the reference sample.Although these two correlation factors can be partially cancelled our in data analyses,the difference between these two factors in the low relative momentum region is so large that the distortion on the analysed results of two-pion interferometry from multi-pion interference becomes a serious problem when the pion source has a small radius and the pion multiplicity of event is high.The distributions of multi-pion correlation factor Cn-2(q) can sensitively reflect the multi-pion correlation effects in the events The analyses of multi-pion correlation factor for two Bevalac streamer chamber data samples of 2.1AGeV Ne+Pb and 1.8AGeV Ar+Pb collisions show that the multi-pion correlation effect in the former data sample is greater that in the latter.
High Energy Unequal-nuclei Collisions and Relaxation Time in Fokker Plank Equation
BAI Ge, YANG Wei, LI Jia-Rong
1993, 17(1): 57-64.
In this paper,the time evolution of high energy heavy ion collisions is described by Fokker-Planck Equation.The rapidity distribution of the final state particles is analysed with this model for 16O and 32S particles beams of 200AGeV.The relaxation time for various systems are determined.Results comparable to the usual empirical data are obtained.
Deuteron Properties in the Chiral Quark-Soliton Model
XU Xiao-Ming, QIU Xi-Jun
1993, 17(1): 65-68.
The deuteron ground state mixed with 3D1 state is caused by the tensor potential of one meson exchange between two quarks.The properties of the deuteron 3S1+3D1 ground state are calculated with the chiral quark-confinement soliton model.
Effect of Spectroscopy Amplifier Parameter on Identification of Light Charged Particles by Pulse Shaping Analysis Method
WANG Jin-Chuan, XI Hong-Fei, GUO Zhong-Yan, ZHAN Wen-Long, ZHU Yong-Tai, ZHOU Jian-Qun, LOU Guan-Hua, SU Hong
1993, 17(1): 69-77.
The pulse shaping analysis method is applied to identify the light charged particles emitted from 12C(46.7/MeV/u)+58Ni reaction by using the CsI(T1) scintillator detector with photodiode readout.In the experiment,it is found that the particle identification greatly depends on the choice of spectroscopy amplifier shaping time constant.The problem is investigated on the basis of Laplace transformation method.The experimental phenomena have been successfully explanined.
Nuclear Superdeformed States
ZENG Jin-Yan
1993, 17(1): 78-96.
The recent development of the investigations of nuclear superdeformed (SD) states are briefly reviewed with emphasis on the phenomenological analyses of nuclear SD rotational bands,including the determination of the angular momenta of SD bands,the variation of the kinematic and dynamic moments of inertia with rotational frequency and their mutual relation,etc.A plausible scheme to account for the so-called "identical"SD bands is given,which seems to be consistent with the available microscopic calculations and in which no pseudospin alignment is involved.