1989 Vol. 13, No. 8
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Charged particle multiplicity distributions in pp collisions at 400GeV/c have been studied by using the LEBC films which were offered by CERN NA27 Collaboration.
The corrections to the raw data are described.The results are compared with data at other energies.It is shown that the charged particle multiplicity distribution for the nonsingle diffractive process has KNO scaling behavior,whereas for the inelastic process shows a deviation from KNO scaling up to ISR energy.
The paper briefly describes the hardware configuration and software components of the BES (Beijing Spectromenter) on-line data acquisition system,and summarizes the development of this system we completed in the recent two years.A successful run of the on-line system has been performed in the BES'S cosmic ray test.
The production of large-transverse-momentum photons from Quark-Gluon Plasma (QGP) is discussed,and is used to analyze the high multiplicity event found in the Japanese-American Cooperative Emulsion Experiment (JACCEE).The theoretical result turns out to fit the experiment well.Thus the production of large transverse momentum photons provides an experimental signal of the QCD phase transition.
An exact solution of the Naive Schwinger model on lattice is found.The continuous limit of the solution is discussed.The result is that the Naive lattice gauge theory can not cut off the unphysical states of the Schwinger model in the high-energy limit.
In this paper the radial solutions of the Dirac equation in a metric with spheroidal symmetry are given.It is shown that there exists no quantum bound states of Fermions about the Schwarzschild black hole.Some cases are discussed,one is a soliton wave of the temporal state,which provides a new insight for checking the existence of a black hole,the other is a solution of the stationary state which describes the accretion and vaporization of the black hole.
Following the method developed by the authors,recently,the equation of state of hot nuclei(238U in concrete) before break-up was investigated numerically.The isotherms are drawn in the plan of the general pressure P versus volume VRT. They are similar to those of Van der Waals gas.The critical temperature of phase transition should correspond to the isotherm with one turning point only.It turns out that the data of mass yield distribution can be reproduced by many pairs of parameters T and VRT (freeze-out temperature and freeze-out volume) varying in certain range.For each isotherm (each T),the data are always best reproduced by the value of VRT located at the maximum general pressure within two phases coexistence region.
In this paper we calculate the contribution to the amplitude of 0νββ decay,which is mediated by the heavy neutrino,from the mechanism of pion-single-charge-exchange and compare it with the contribution from the mechanism of the pion-double-charge-exchange.We find that the substantial contribution of the pion degree of freedom to 0νββ decay in nuclei is only from the mechanism of the pion-double-charge-exchange.
In this paper,the mass effect on the internal motions in modeled three-body systems has been analysed in detail.Two new modes of internal motion in three-body systems have been found.
6Li(d,dd) α reaction induced by 7.3—10.6MeV deuterons was studied under collinear condition.An enhancement in differential cross section beyond the well known QFS and FSI contribution was observed at incident energy of 9MeV.It is the state of quasi-molecule resonance of chain configuration.
The angular distributions of fission fragments for a series of compound nuclei formed in the bombardment of 181Ta,197Au Pb and 209Bi by 12C ions and in the bombardment of natural lead by 14N ions were measu ed with mica track detectors and gold surface barrier detectors.It is shown that all experimental data for the fission fragment angular distributions can be fitted by the statistical scission model of fission fragment angular distribution.
Resonant structures appeared in the excitation functions for the 16O+20Ne elastic scattering have been studied by using the nuclear molecular orbital theory.The theoretical results agree well with the experimental data.
The abundant data about the high-spin states (up to Iπ～30+) of ground bands in actinides even-even nuclei,obtained by heavy ion Coulomb excitation,are used to test the various formulas now available for rotational spectra.From the analyses of energy spectra,moments of inertia and γ-transition energies it is found that Wu-Zeng's formula is better than all the rest 2-parameter formulas,including the widely used Harris' formula.In some cases the prediction by Wu-Zeng's formula may be helpful for judging the reliability of some observed data.
A model taking into account both fragmentation and transfer process agrees well with experimental data on projectile-like-products momentum distribution resulting from heavy ion collisions in Fermi energy domain and in relativistic energy domain.The resulted reduced widths σ0 are given for both fragmentation and transfer process respectively.
The chiral SU(2)L SU(2)R σ-Model with both spontaneous and dynamical symmetry breaking is investigated and massive π mesons are obtained.The physical mechanism of how π mesons acquire mass is discussed.
A modified lattice Schwinger model is proposed and its exact ground state is found.
The variational-cumulant expansion method has been extended to the case of lattice SU(3) Wilson model.The plaquette energy as an order parameter has calculated to the 2nd order expansion.No 1st order phase transition in the d=4 case is found which is in agreement with the monte Carlo results,and the 1st order phase transition in the d=5 case is clearly seen.The method can be used in the study of problems is LGT with SU(3) gauge group.
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