## 1989 Vol. 13, No. 9

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**Abstract:**

The resistance,positron lifetime spectra and the Doppler broadening energy spectra of high T

_{c}supercondoctor Y-Ba-Cu-O are measured simultaneously near the phase transition temperature.It is shown that the critical temperature of the material is about 90°K,and the positron annihilation mean lifetime m as well as the Doppler broadening parmeters H and S are in a state of irregular vibration within the phase transition region.This pheuomenon may probaley relate to the instability of the crystal structure,and seems supporting the uperconducting mechanism in which the bipolaron theory a major role.

**Abstract:**

We give here the one loop results of the numerical calculation and events generation of Bhabha scattering at LEP/SLC energy.EM radiative correction and hard collinear photon effect have been taken into consideration.

**Abstract:**

The structure of the BES main drift chamber and arrangement of cosmic ray tests have been described briefly,The main test results of the chamber performance have been given.There are S-T relations with good linearity in the cells.The spatial resolution of 210—240μm has been obtained for single wire.The energy resolution corresponding to 40 samples in the chamber is 8.7%.

**Abstract:**

We take lattice φ

^{4}theory as an example to illustrate one of the principles for the choice of the trial action in variational-cumulant expansion approach on lattice.

**Abstract:**

Using the empirical formula on R(x)=F

^{N}

_{2}(D) proposed by the authors and generalizing the method used in calculating the processes p+p(p)—γ+X,the differential cross sections and the total cross sections for high p

_{T}direct photon productions in p-Al collisions are calculated,and some new predictions are obtained.These theoretical results are to be checked by future experiments.

**Abstract:**

It is poined out that the relative weight between (3/2)

^{+}and (1/2)

^{+}baryons has no effect on the yield of long-lived baryons in final states,but changes the yield of (3/2)

^{+}baryons considerably.By analysing the experimental data we show a very strong suppression factor of (3/2)

^{+}baryons of the order 0.3, and as a result the yield of the final state baryons and their ratio all agree with experiment.

**Abstract:**

Using the Maximum Entropy Method (MEM),we investigatied the high energy limit in hadron-hadron collisions.Different kinds of entropy are defined and the role of physical constraints in maximizing the entropy are emphasized.Definite prediction for the average multiplicity in high energy limit and the interpolation between this limit and the existing data are obtained.

**Abstract:**

In this paper,based upon analysing the various factors which might cause the overbinding of

^{5}He,we make a proper adjustment for the wave function of the core nucleus

^{4}He.With the adjusted core wave function and various Λ-N interactions,we calculate the Λ-hyperon binding energy B

_{Λ}(

^{5}He) of the

^{5}He ground state and obtain a reasonable agreement between the theoretical and experimental values of B

_{Λ}(

^{5}He).Thus, the

^{5}He overbinding problem could be explained.

**Abstract:**

A method to calculate the effect of the Pauli exclusion principle in multiparticle and hole state densities has been proposed.As the physical application,the exact Pauli exclusion correlation values have been calculated in the equidistant spacing model.The exact Pauli exclusion correlation values are obviously larger than that used before,such as the kalbach's values.Correspondinyly the internal transition tates and equilibrium exciton number have been changed.

**Abstract:**

By comparing the results calculated by the locally harmonic approximation methed and the numerical solution for the FOKKER-PLANCK equation with a nonlinear force,the reliability of the locally harmonic approximation has been examined and discussed in a considerably wide range of nuclear temperature and viscosity.

**Abstract:**

In this paper the formula for the matrix elements of an one-body tensor operator of the many-particle system between two PDHF states is given.The B(E2) values of the electric quadruple Gamma transitions between the low-lying states of even-even titanium nuclei are calculated,and the evidences exhibiting the band intersection in the yeast are found.

**Abstract:**

The Structure of hypernucleus

^{10}Be is studied by using

^{9}Be+Λ two cluster model.Using the transition density matrix of

^{9}Be,the folding potential of ΛN interaction is obtained.Taking into account the glue-like role of Λ-hyperon in the hypernucleus,a contraction factor S is introduced into the density matrix of

^{9}Be.The eigenvalues E

_{I}of

^{10}Be are obtained by solving the channelcoupled equations.

**Abstract:**

In view of the proton boson and neutron boson coupling,all possible dynamical symmetries in the proton-neutron interacting boson model are discussed.The symmetries are found to be in four types,of which some are newly discovered.The commonly used IBM2 computer code NPBOS is checked through group chain method.It is found that most NPBOS calculations are correct,except in cases where Q

_{π}Q

_{π}and Q

_{v}Q

_{v}is included in the Hamiltonian.Using NPBOS,

^{150}Sm and

^{152}Sm are studied.

**Abstract:**

This paper investigates laser-induced meutron radiative capture reaction.There exist great discrepancies between the existing theoretical and experimental studies on this subject.From Einstein's general theory about emission and absorption of photon,a formula to calculate the laser enhanced neutron width for nuclear resonance has been given with a feature that the width is expressed in terms of model-independent measurable parameters.The measured widths have been analysed and compared with the calculated.The possibility to observe the effect in the near future has also been discussed.

**Abstract:**

In this paper string tensions of both the modified Naive and Susskind lattice Schwinger models which have the solvable exact ground states are calculated exaqctly.The linear potential between quark and antiquark infinitely seperated is derived for both Naive and Susskind lattice Schwinger models.No phase transition occurs when a tends to zero and this coincides with the continum theory.

**ISSN** 1674-1137 **CN** 11-5641/O4

Original research articles, Ietters and reviews Covering theory and experiments in the fieids of

- Particle physics
- Nuclear physics
- Particle and nuclear astrophysics
- Cosmology

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