1999 Vol. 23, No. 08
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The decay J/ψ→γπ0π0 is studied with 7.0×106 produced J/ψ events collected by the Bening Spectrometer(BES) with the tugger mode senseuve to both chmped and neutral final state at the Bening Electron-Positron Collider(BEPC), The evidences for the existence of fJ(1710) and E(2230) in this channel are presented, and the corresponding masses as wen asthe product branching ratios are obtained.
The energy spectra of intermediate-mass fragments (IMF) (3≤Z≤16) have been measured from 6° to 110° for 40Ar+natAg reachon at 30 MeV/u. The energy spectra were analyzed by the moving source model. The natUres of the projechle-like source, target-like source and mid-rapidity source as well as the evolution with angle and nuclear charge were discussed. Two intermediate mass fragments, measured by correlation method in forward angles, come from two sources. One comes from projectile-like source, and other one mainly comes from intermediate source respectively.
An experimental method of measuring backward sputtering induced by fast neutron is described. Backward sputtering yields of 10 malterials of Mg, Al, Sc, V, Fe,Co, Cu, Zr, An and type 316 stainless steel are measured and compared with forward sputtering yields. It is found that the ratios of backWard to forward sputtering yields depend on the kinds of reactions. The present results are compared with other experimental resultS and explained using sputtering theory.
The problem about ηc decay into two vector mesons, such as ηc→ρρ, K* K*,φφ. are discussed in the Bethe-Salpeter framework. Both constituent quark mass and intrinsic quark transverse inchon inside the final state mesons are taken into account and their implications are discussed. The result shows that ηc→VLVT is stricly forbidden. Quark transverse momenta has apparent effect of enhancing the decay rate.Though both factors are included, the theoretical value is still smaller than the experimental data.
We investigate the vacuum state of (2+1)-dimensional U(1) lattice gauge field theory, and derive the parameters of the continuum vacuum wave function in great details. The numerical results from the truncated eigenvalue equation method are also provided.
in this paper we use the Batalin-Fradkin-Vilkovisky (BFV) formalism to study the quanhzation of a scalar QED with Chern-Simons term. The conserved laws of energy, momenttum and angular momentum at the quantal level of the system are obtained. The property of frational spin of the system at the quantal level is pointed out.
The experimental results on maximum pseudo-rapidity ηmax distribution in the charge exchange process e+p→e+n+X is discussed in thes paper. The contributions of reggeon from regge phenomenology and π+ -exchange from pion cloud medel is calculated. The results show that neither the Rρ-exchange nor the pion cloud model alone can explain the experimental data well, but after considering both these two processes together, by using Month Carlo simulahon, a good agreement betWeen theoretical results and experimental data is found.
The influence of the I=1 staggering and the fluctuation in observed γ-tyanstion energies on the spin assignments of superdeformed bands is taken into account properly. An improved approach for removing the fluctuations from the observed y transition energies is proposed. The smoothed transition energies are fitted by the ah expression or its modification to assign the spins of the superdeformed bands in the odd-A nuclei in A≈190 region. The assigned spins for some superdeformed bands are different from those given in other approaches.
Alignment additivity of the superdeformed (SD) bands in odd-odd nuclei 194Tl and 196 Bi is investigared with the level spins determined by the Cranking Bohr-Mottelson Model. The alignments of four of the six SD bands in 194Tl can be accounted for from the additive contributions of SD bands of the neighboring odd-proton and odd-neutron nuclei, while that of the SD band 196Bi(1) can not.
The properties of proton-rich and their mirror nucleus in 2sld shell have been investigated by relahvistic mean field theory. The results obtained by relahvistic mean field theory are in good agreement with experimental data.
Based on the two-body correlation dynamics(TBCD) introduced by Wang et al., we have taken the bine dependent single pride states as working basis to derive the tWo-body correlation transport theory (TBCTT) for describing the dynamical process of HIC. ms theory contains all possible two-body correlation, the timedependent mean field and antisymmetric effect to provide a microscopic descriphon for the dynamical transport process in HIC. As a testing step, we take QMD code without collision term to preduce the bine-dependent coherent single particle basis for TBCTT. Comparing and calculating the different interaction such as Skyme, Coulomb and Yukawa are performed, it indicates that Coulomb and Yukawa intenahon have important effects in HIC, and show that all behaviors of quantities studied are similar to dynamical process of heavy ion collision. The conservation laws of dynamical process of heavy ion collision, the momentum and number of particle are very good,except the energy conservation as no coupling in thes work.
1.65h 95Ru was produced and studied by y ray spectroscopy of 92Mo(a, n)reaction, 34 of the 130 obversed y rays following 95Ru decay are new. According to coincidence relations, 29 new γ rays were flited into level scheme, the placement of 7 γ rays in level scheme were confirmed, 3 new levels were assigned, a modified and expanded decay scheme was proposed.
An analytic treatment of multi-bunch potential well distortion for a twobeam storage ring is presented. The longitUdinal wake effects are separated into: the mode loss, the synchrotron tUne shift (both due to potential well distortion) and the coherent multi-bunch coupling. Here, only the first two effects are studied. Resulting simple analytic formulas describe the mode loss and the synchrotron tune shift experienced by a given bunch within the two-beam, as a function of the high order mode's parameters. One can get immediately a simple quantitative answer in term of the mode loss and the synchrotron tUne shift experienced by each bunch form these formulas, so we can know how to modify the existing configuration of parasitic cavity resonance (via frequency tuning) so that the resulting potenhal well distortion effects are minimized. When the RF cavities are symmetrically distributed about the interaction points, the two beams will have same beam loading effects, so we can compensate the phase shift of the tWo beam using the same method as in one beam case.
Direct hard PhotoProduction of J/ψ and γ at LHC Pb-Pb collisions with CMS energy 5.5ATeV, and Ca-Ca collisions with CMS energy 7ATeV, are discussed in the process: A+A→A+J/ψ(γ) + X. It turns out that the processes can be used to testing the gluon distribution in the nucleus, as well as to studying the mechanism of large Pt gluon and heavy quark fragmentation of J/ψ.
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