1995 Vol. 19, No. 04
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Based on 7.8×106 J/ψ events collected by the BES at BEPC, through study of the hadronic decays J/ψ→φπ+π－ and J/ψ→ωπ+π－, the branching ratios of the processes and the mass positions and the widths of f0 are obtained. The angular distributions of J/ψ→φf0,f0→π+π－, are fitted and the helicity amplitude ratio of this process is first given.
The pseudorapidity distribution of charged particles produced in pp collisions at 400GeV/c was measured by using LEBC films offered by CERN NA27 collaboration. The scaled factorial cumulant moments have been caloulated. Comparing with the results obtained from Monte Carlo events with the same single particle spectrum and no correlations, it is shown that for broad mixed multiplicity distributions, a significant part of K2 is coming from the single particle fluctuation due to the fluctuating multiplicity. The factorial cumulant moments obtained by using the star correlation integrals reduce significantly the statistical errors of the higher order cumulant moments, but the essential conclusions remain unchanged.
The angular distributions of the fragments in the range of 4π solid angle for the 600 MeV 40Ar+197Au reaction have been measured using the beam-off γ-ray spectroscopy technique. The features of the fragment angular distributions and the reaction mechanisms of the production of fragments have been discussed.
The contributions of the double Pomeron exchange to the J/ψ production inhigh energy p+p(p) collisions are calculated using different models for parton distribution functions inside the Pomeron(P). For the Ingelman-Schlein model in which gluons dominate in partons, the cross sections in high energy increase smoothly with as In2S or InS. The total cross section σ(S) is about 102－103nb in the TeV energies. For the Donnachie-Landshoff model in which the P are considered as something like isoscalar photons with C=+1 the cross section behavior increasing with energy is a little bit complicated. In same energy range, the cross sections are only 1-3nb which are smaller than that of the former case by 2—3 order of magnitude. So, if we assume the parameters of the above models are reliable, then these J/ψ production processes should be a good place for testing these models.
Starting from the transformation property of the action integral of a system under the local and non-local transformation, we derive the generalized Noether's identities connecting with non-local transformation. The applications of the theory to the Yang-Mills field with high-order derivatives are presented. A new conservative PBRS charge is found which differs from BRS conservative charge. The other conservative charge connecting with non-local transformation is also obtained.
0-heavy meson bound states are discussed by using the Bethe-Salpeter (B-S)equation at the instantaneous approximation. In terms of the heavy flavor mass expansion method, the masses for mesons D0, D±, B0, B± are calculated at first order approximation. Comparisons of our results with experimental data and with some theoretical calculations from other method are given.
In this paper, gauge constrained conditions and quantization of SU(N) gauge theories are analysed by means of Dirac's formalism. In the framework of algebraic dynamics, gauge invariance, Gauss law and Ward identities are discussed. With use of the version of conservation law in correlation dynamics, the conserved Gauss law and Ward identities related to residual gauge invariance can be transformed into initial value problems.
Based on interacting gluon model, leading particle rapidity distributions for 100 GeV p+Ag collisions are calculated and compared with experimental data. The results are in a good agreement with data when using a more sophisticated collision geometry and including final fragmentation process.
Using the Glauber Multiple scattering theory, we analyse the experimental elastic differential cross section of antiproton-4He scattering at low-energy. It is found that the character of multiple collision is still dominant as the antiproton energy is as low as 19.6 MeV. The same conclusion is obtained by comparison with the optical model calculation.
Identical bands of odd-A superdeformed nuclei in the A～190 mass region have been investigated using triaxial-particle-rotor model within the framework of the BCS pairing correlation. Three pairs of identical bands (191Au, 191Hg(b1)), (191Hg(b2),193Hg(b2)), and (191Hg(b3), 193Hg(b3)) are analyzed. It is pointed out that the identity in the γ-transition energies in these bands may be the result of the occupation of some special orbitals.
The properties of the band in even nuclei of 166Hf94—170Hf98 are investigated using cranking shell model with PNC method. The band crossing frequency, the interaction intensity between yrast and yrare bands, the aligned momentum, and the moment of inertia are calculated. The comparison between the calculation and experimental data shows a good agreement with each other if Lund systematic parameter is used for the Nilsson potential.
We generalize the relativistic Vlasov-Uchling-Uhlenbeck model to include the kaon mean-field potential and the final-state rescatterings of kaons with nucleons,and use it to simulate the subthrcsbold kaon production from the collisions of two Ca nuclci at an incident energy of 1GeV/nucleon. The effects of the vector meanfield potential and the kaon rescattering on the final-state properties of kaons are analyzed. From the calculated results it is found that the effect of repulsive vector potential due to nucleons on the final-state kinetic energy spectrum of kaon is similar to that for the kaon final-state rescattering and leads to an significantly enhanced yield of kaons with large momenta in the laboratory system. However, the effect of the kaon rescattering on its kinetic energy spectrum is reduced considerably by including the repulsive vector potential. This indicates that these final-state interactions of kaons with nucleons are not negligible in order to evaluate reasonably thekaon energy spectrum and angular distribution.
An energy dependent optical potential for 12C+12C system is established based on the analyses of the angular distributions of the elastic scattering in the energy range of 70-160MeV. This potential can well reproduce the excitation function for 12C+12C elastic scattering in the same energy range.
The neutron dose equivalent produced by skyshine was calculated using MORSE program. For these calculations, the neutron sourse was enclosed in a hollow concrete cylinder. There were two cases, one was the cylinder with concrete roof shielding, the other was without a roof. The sourse energies of 2.38 MeV, 14 MeV and giant resonance (G. R) neutron were calculated separately. We have compared the effects of different models, such as different sourse emission solid angle and different scattering media. The results can be applied for the estimation of radiological impact to invironment and the design of radiation protection on the particle accelerators and other nuclear facilities.
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