1994 Vol. 18, No. 12
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Adopting a nuclear collision geometry and two-component model of hadronhadron interaction,a Monte-Carlo generator on p-N and p-A interaction has been established,Using this generator,the inelasticity distribution,average inelasticity of p-A interaction and their dependence on the mass of target have been studied.
The discriminant analysis method in Multivariate Statistical Theory is used to handle e,π,μ separation in BES.The principle of the discriminant analysis method is described,the unstandardized discriminant functions(responsible for particle separation)are derived,the discriminant efficiencies for e,π,μ are given and the results are compared with those obtained from conventional way.
Based on the three-fireball model and the picture of hadronic resonance decays.the transverse momentum and pseudorapidity distributions of negative particles in relativistic heavy ion collisions are obtained and compared with the experimental results of 200 and 60GeV/N 16O-An interactions.
The p+p(p)→p+J/ψ(Υ)+X processes for energies ranging from ISR to SSC are discussed. Assuming that Pomeron(P)have parton distributions and dominated by gluons with behavior as when x.is small,we calculate carefully the cross sections for the above hard diffractive processes and of"background"DrellYan Processes by tab lug two main sub-diagrams in the lowest order of QCD.In contrast to InS increasing with S for the background cross sections,the hard diffractive ones increase as(InS)2,hance the latter would be greatly beyond the former at TeV energies.We shown that this property is universal for other hard diffractive processes.So,if our assumptions about P are right,they would provide a new method for detecting physical particles at superhigh energies.
The one-loop corrections to the process t→W'b from the Pseudo Goldstone bosons in the one generation Technicolor model are calculated.The dependence of the corrections on the top quark mass and Pseudo Goldstone bosons mass are discussed.The total corrections to the decay rate change from 0.6% to -2.0%for mt in the range of 100-200GeV.
We analyse the effects induced by η-η＇mixing angle and the production of L=1 mesons on the multiplicity rates of η and η＇mesons.The results show that the influence of the production of L=1 mesons on the multiplicity rayes is quite importment.When we take only this factors into account,the calculated multiplicity rates are agreement with experiment.
Based on the two geometrical pictures. namely independent N-N collision and participant-picture,the newly published data of transverse energy distributions in high energy p-A collisions are analysed.The influence of the choices of various model parameters is discussed and compared to the results in A-A collisions.
Starting from the shell model configurations and the effective nucleon-nucleon interactions,a microscopic approach is applied to study high-spin states for the isotopes 126Ba,128Ba and 130Ba.The low-lying states and the band built upon aligned (h11/2)proton pair configurations are considered.Energy levels and backbendings are reproduced well.For the yrast band,the dependence of the strength of interband interaction on the coupling operator is discussed.
In this paper,we prove analytically that the parton evolution model can provide a physical basis to the double x-rescaling model. Then we describe the nuclear shadowing and antishadowing effect in the small x region using the modified Alteralli-Parisi equation to improve the parton evolution model.The unified description of the EMC effect,the nuclear shadowing effect,and antishadowing effect is given without introducing the nuclear shadowing factor.Finally,we explain the experimental data of the Drell-Yan process with the improved parton evolution model.
A comparison of two different nuclear structure models for 12C+12C scattering is made.The comparison shows that the α-particle model of 12C gives the better results.
The B(E2:)values and ground band energy ratio R=,are often used as indicators of the collectivity in nuclear motion.A great effort has been paid to understand systematically the relation between these quantities and the calculated deformation parameters through a standard potential energy surface approach.It is found that the B(E2:)values are dominantly determined by the equilibrium(static)deformation of nuclei.The existing NilssonstrutinskyBCS approach can reproduce nicely reasonable deformation values for a great variety of even-even nuclei, from Z=30 to actinides,while the energy ratio R reflects the whole structure of the potential energy surface,such as the stiffness and unharmonisity.
The three-body interacting items are introduced in the IBM Hamiltonian and a simply corrected formula of the O(6)energy spectra is given.The caculations for some nuclei near A~70.130.190 regions show that the agreement between the theory and experimental data is greatly improved.
A discussion on the energy spectra and E2 transition rates of the even-even Xe isotopes with A=116 to 132 is carried out in the framework of neutronproton Interacting Boson Model.With the quadrupole interactions among like coherent nucleon pairs S and D being taken into account,the staggering phenomenon in the quasi-γ bands of these nuclei are improved. The calculated results of the low-lyingenergy levels agree with the experimrntal data quite well.
A method is described which experimentally determines the trajectory sensitive parameter β of NdFeB rectangular magnet used for wiggler of Beijing Free Electron Laser(BFEL).The parameter β expresses the contribution of single magnetic block to electron trajectory.The magnetic blocks are chosen and optimized according to their β values, and the deviation of electron trajectory in the wiggler can be improved.
The boson resonance state X is produced in company with f0(975)in the J/ψ hadronic decay process.If the X particle decays into a pair of pseudoscalar mesons its spin-parity is Jpc=(odd)－－.The helicity formalism of angular distribution of the process has been given. How to discriminate 1－－ meson from 3－－ meson for the X particle has been discussed. We think that the X1(1573) which has been observed in the four prong channel(K+K－π+π－) and in company with f0(975)(→π+π－)by BES collaboration may be a new resonance state.
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