1991 Vol. 15, No. S4
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The charge-changing cross sections of 200 A GeV S and its fragments P, Si, Al, Mg, Na and Ne in collisions with Cu target are measured. It is shown that the cross sections of secondary fragments are larger than those of primary beams with the same charges. The electromagnetic spallation cross sections deduced show a dependence on the charge of projectile which is consistent with theoretical prediction.
The pseudorapidity distributions for charged particle multiplicities 8-12 produced in pp collisions at 400 GeV/c have been measured by using the LEBC films offered by CERN NA27 collaboration. The c.m.s. forward hemisphere multiplicity distributions at fixed total multiplicities have been analyzed by using cluster model. The results show that the average cluster size is related to whether the leading-particle effect is taken into account.
Cross sections and recoil properties were measured for target residues from the interaction of 181Ta with 45 MeV/A 12C ions by using thick target-thick catcher foil techniques. The mass yield distribution measured experimentally was compared with a statistical multifragmentation model. A comparison of the linear momentum transfer calculated from the average forward recoil ranges with our previous results indicates that in 45 MeV/A 12C-induced reactions, the linear momentum transfer in central collisions increases with target mass,which is in good agreement with the calculations based on leading particle models.
Activation technique has been used to measure the cross section for 58Ni(n,p),60Ni(n,p), 62Ni(n,α) reactions in the neutron energy range 13.6-17^ MeV. The covariance matrixes for measurement error are calculated. The range of measurement error is 3%-7%. Evaluations for 58Ni(n,p),60Ni(n,p), 62Ni(n,α) and 54Fe(n,p) cross section are made.
In this paper, the quantum probability functions are calculated for 10-dimensional compact baby universe model. We find that the probability for the Yang-Mills baby universe to undergo a spontaneous compactification down to a 4-dimensional space-time is greater than that to remain in the original homogeneous multidimensional state. Some problems about large-wormhole catastrophe are also discussed.
Probability Pi for the production of i-quark jets (i=u,d, s, c and b) in the e+e- annihilation has been studied based on the electroweak unified standard model. Probability Pi is a function of energy √ . The calculated component ratios of Pu:Pd:Ps:Pc:Pb are 4:1:1:4:1 for √ < 30 GeV, 7:9:9:7:9 for √ =mz=91.16 GeV and 1:1:1:1:1 for √ =78 and 117 GeV, respectively. Using Pc and Pb we have calculated the yields of charmed and bottom mesons in e+e- annihilations in the range of √ =10-178 GeV.
By using sum rules in quantum mechanics, the upper and lower bounds on the electric dipole transition widths of the ψ (3770) are estimated. It indicates that the experimental values given by the Mark III Collaboration are larger than the theoretical values evidently.
Based on the model of the expanding hot quart-gluon plasma fireball created in ultrarelativistic heavy-ion collisions, we investigated the rates of the s-quark and K- meson productions after considering particle distribution in the fireball and by using the relativistic hydrodynamic equation. It is shown that the particle distributions enhance the production rates strongly.
On the assumption that the rapidity of produced particles by the fireball is distributed with equal probability under the constraints of energy conservation and transverse-momentum cutoff, the multiplicity distributions for different rapidity window are calculated by using the multisource medii. The calculated results fit the experimental data well.
We calculate the W-boson electric dipole moment in the Weinberg-Higgs model in which the CP violation is mediated by charged Higgs boson exchange, and compare our results with the others given by the literature.
Chiral Ward-Takahashi identities with composite fields are applied to investigate mass spectra in (2 + 1) dimensional chiral gross-Neveu model. The fermion mass and bound state spectra are obtained, which are in agreement with large-N expansion in the lowest approximation. When the chiral symmetry is an approximate one, we obtain the PCAC.
A phenomenological analysis of the superdeformed bands in even-even nuclei is given. A method has been developed to determine the spins in the superdeformed bands based on the relative energy spacing.
Fifteen superdeformed bands in seven nuclei of the A~190 region are analyzed based on a phenomenological model. An overall and excellent agreement between the calculated and observed spectra Eγ kinematic moment of the inertia j(1) and dynamic moment of the inertia j(2) is obtained for all superdeformed bands in the A~190 region.
The Feynman-Hellmann theorem widely used in nonrelativistic quantum mechanics is applied to relativistic two-body wave equations to deduce the meson mass formulae. It is shown that the wave equations considered in this paper are unable to describe the short-range interaction of quarkonium reasonably.
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