1994 Vol. 18, No. 11
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A parton model based on perturbative QCD is developed for the description of ultrahigh energy interaction between cosmic rays and air nuclei.A LLA QCD calculation of jet production cross sections in proton-proton scattering and a hadronization scheme based on independent fragmentation model are presented.A number of parameters in the hadronization scheme are so selected that the basic features of hadronic production in e+e－ collision covering C.M.energy region from 14 GeV to 91 GeV can be reproduced. A Monte Carlo generator is constructed to reproduce the basic characteristics of proton-antiproton scattering in the C.M.energy region from 60 GeV to 1800 GeV and to extrapolate smoothly to ultrahigh energy region extending to 22 TeV.
The pseudorapidity distributions for charged particles produced in pp collisions at 400GeV/c have been measured by using the LEBC films offered by CERN NA27Collaboration.The scaled factorial moments have been calculated.It is obtained that the intermittency exponent increases with increasing moment-order and decreases with increasing average multiplicity,the anomalous fractal dimension dq increases with q.It shows that the multiparticle production in hadron hadron collisions possesses a self-similar cascade property.
Using G-moment method,the multifractal analysis has been performed for the experimental data of the pseudorapidity distributions of charged particles produced in pp collisions at 400 GeV/c.While the splitting steps are small, the obtained generalized dimensions Dq are different(1>D0>D1>D2…);the spectral functions f(αq) are smooth, downward coneave with a peak at α0;the rescaled spectral functions f(αq) possess universality in the region of αq≤1. These results are consistent with other experiments.
Intermediate mass fragments(2Z≤11) emitted from 294 MeV 20Ne+159Tb reaction have been measured by △E-E telescope counters at the angle of 10°—150°region.The energy spectra of the fragments at back angle(>90°) have bell shape,and their peaks locate near the Coulomb barrier of exit channel.The analysis of the energy spectra has been done in terms of moving source and indicate that all the fragments are emitted from a common source,the compound nuclei formed in incomplete fusion process.The charge and angular distributions of the fragments originated from the asymmetric binary decay of the formed compound nuclei have been calculated based on statistical GEMINI code,and the results are in well agreement with the experimental data.
A Monte carlo generator of Chou-Yang model to describe proton-proton soft scattering is developed based on pp NSD scattering data and the subtraction of the contribution due to hard scattering.This generator can be used for the description of soft hadronic NSD proton-proton interactions from 26 GeV to 22 TeV.Major experimental results observed on colliders are reproduced reasonably by using the generator combined with the calculation of large pr jet production and hadronization.A decrease of inelasticity with the increase of energy is predicted.
We investigate the phase transitions of Abelian lattice gauge theories at finite temperature with the variational cumulant expansion.Our results are in good agreement with the exact resaults and the basic predictions made by Sevtitsky and Yaffe.
1+1-dimensional U(1) Higgs model on the circle is examined.Non-contractable loops are constructed and Sphaleron configurations are presented.
We propose a new quantization scheme with which and the equation of motion the quantization problem of both independent and dependent interacting fields in QED can be solved simultaneously.When the external gauge field Aμ(s)≠0(i.e.the Fermion field ￠(x) and the electromagnetic field Aμ(x) are independent) our scheme gives the same result as the usual quantization approach.When the external gauge field is absent the usual quantization conditions are failed since it is not compatible with the equation of motion,meanwhile our scheme is still valid.These results are demonstrated with solvable QED in 1+1 dimension.
With the effective interactions consisting of a pairing force,a quadrupole pairing force and a quadrupole-quadrupole force among valence nucleons,the microscopic approach based on the generalized Dyson expansion theory is applied in studying both the low-lying and high spin states for the isotones 154Dy,156Er and 158Yb.In the truncated state space,the configurations(sd)N and (sd)N-1,+neutron-pair are assumed,respectively,for the low-lying and high spin states,although the same values of strength parameters are taken in the numerical calculations in the two subspaces.The calculated results are in good agreement with experiment,especially the data of first backbendings are reproduced satisfactorily.
A new method for the relativistic calculations of particle hole and delta-hole excitations of pious in nuclear matter is given.We point out the difference between the usual methods and ours.The dispersion relation of the pion meson including virtual particle-hole excitation is calculated and compared numerically with that of the non-relativistic case.The formulae of relativistic delta-hole excitation of pious in nuclear matter are also given.
The angular and linar momentum transfered to target residue on 20 to 180MeV/u 16O+197Au system are calculated with BUU(Boltzmann-Uehling-Uhlenbeck) model in which the angular momentum conservation is added.The dependence of angular and linar momentum on impact parameter and incident energy is discussed.The deviations between calculated values of(1mt) and those from viola system are compared.The results of the simulations suggest that the saturation of angular momentum transfer with incident energy increase mainly comes from the loss of capture ability of the target on projectile.
A method of solving the transport equations for quarkgluon plasma beyond the Abelian dominance approximation is given.The transport coefficients of colored quark-antiquark plasma are calculated using this method.The effects of non-Abelian color field on them are discussed.
Based on the cluster structure of 4N-nucleus,a parity-dependent potential is derived by using a proper nuclear orbital wave function and the folding method.The potential is in analytical form with no adjustable parameter.The angular distributions of the 12C-16O elastic scattering is studied using this potential and the characteristic feature of the data is well reproduced.
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