1989年, 第11卷, 第2期　
刊出日期：1989-03-15

  

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  Partial Wave Analysis of Hydrogen Molecule Ion

  BAO Cheng-guang, HE Jin-chang

  理论物理通讯. 1989, 11(2): 121-127.

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  A nonadiabatic procedure is proposed to obtain the eigensolutions of the hydrogen molecule ion. The partial wave behavior of the electron and the proton pair in the three lowest states is investigated in detail in this paper. The overlap of nodes for different partial waves of the protons is found.
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  The Slave-Boson Mean Field Theory of a Modified Periodic Anderson Model

  LI Zheng-zhong, ZHOU Qing-chun, QIU Yang

  理论物理通讯. 1989, 11(2): 128-135.

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  The coherent band states of the infinite U lattice Anderson model with introducing a small dispersion into the f-band are derived in the framework of the slave-boson mean field theory. The temperature dependences of the pseudogap in f-band conduction electrons' density of states near the Fermi level are calculated self-consistently. The calculation is applied to discuss the low temperature properties of the heavyelectron metals. The results show that with decreasing temperature the coefficient of the thermoelectric power Q changes sign below the Kondo temperature T_k, and an additional positive peak will appear at the rather lower temperatures, which are in agreement with the experimental results in CeAl₃.
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  Probability Evolution and Mean First-passage Time for Non-Markovian Processes Driven by Nonlinear Noise

  CAO Li, WU Da-jin, WANG Hui-xian

  理论物理通讯. 1989, 11(2): 137-146.

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  We investigate a stochastic differential equation with general noxilinearity in the noise.With the help of the projection operator techniques, we derive an integro-differential equation for the probability density and an approximate equation for the mean firstpassage time (MFPT). The concrete calculations are made for two important examples.
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  The Study of 0⁺ States in ⁴⁰Ca

  Jian-jun YANG, Hong-qing SHEN

  理论物理通讯. 1989, 11(2): 147-152.

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  In this paper, the low-lying of states in ⁴⁰Ca is studied by using modified surface δ-force and configurations of |0p - 0h>⁰⁰, |2p - 2h>⁰⁰ and |4p - 4h>⁰⁰. The result is satisfactory.
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  On the Direct Mechanism of Photodisintegration of the ⁶Li Nucleus

  G. V. Avakov, B. F. Irgaziev, ZHENG Xi-te, R. Yarmukhamedov

  理论物理通讯. 1989, 11(2): 153-160.

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  In this paper, non-relativistic Feynman diagrams were used to calculate different cross sections of the photodisintegration of the ⁶Li nucleus at the γ-quantum energy 25 MeV≤ E ≤ 80 MeV for different channels, The cluster wave function for the ⁶Li nucleus was used in our calculations.
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  Radial Dependence of the Static and Dynamical Properties of Finite Nuclei

  Guo-qiang LI, Gong-ou XU

  理论物理通讯. 1989, 11(2): 161-169.

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  Both the static and dynamical properties of finite nuclei are evaluated in the framework of self-consistent semiclassical (SCSC) approach. The present results are compared with those of the quantum mechanics. The comparison ehows that the SCSC approach can reproduce the average and collective properties of the finite nuclei very well.
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  A New Mechanism for Low Energy Pion Induced Double Charge Exchange Reaction

  CHING Cheng-rui, HO Tso-hsiu, ZOU Bing-song, Mikkel B. Johnson

  理论物理通讯. 1989, 11(2): 171-179.

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  Using a method developed in theory of double beta decay[1], we propose a new mechanism, namely the two-nucleon pion absorption-emission mechanism for pion double charge exchange reaction at low energies. The calculations are compared with the experimental data of the angular distribution at 50 MeV and the 0° excitation functions of the DCX reactions on ¹⁴C, ¹⁸O with energies < 130 MeV. It is found that the contribution of this new mechanism is very important at low energies.
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  Finite Temperature Semiclassical Approach for Local Potentials

  LI Guo-qiang, XU Gong-ou

  理论物理通讯. 1989, 11(2): 181-187.

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  The nucleon distribution, kinetic energy density, free energy density and entropy density up to the second order in h are derived in a finite temperature semiclassical approach for two local potentials, harmonic oscillator and Woods-Saxon potentiale. The preaent results are compared with the exact quantum reaults for both potentials. The comparison justifies the extension of semiclassical approximation from zero temperature to finite temperature.
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  Multiloop Calculation on the Partition Function of Polyakov's String Model

  SHEN Jian-min

  理论物理通讯. 1989, 11(2): 189-198.

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  Explicit formulaa are deduced for partition functions Z_p, with p ≤ 5, of the closed string. The modular space M_p, may be parametrized by length-twist parameters arising from the quasi-conformal deformations of Riemann surface M_p.
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  The Chiral Anomalies in W and Z Decays

  Chao-hsi CHAN, Qun-qun DU, Jian-xiong WANG

  理论物理通讯. 1989, 11(2): 199-206.

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  Some of the important W^± and Z decay amplitudes, relating to the chiral anomalies of the quark sector in the Standard Model, are given by means of the interactions determined by the effective Lagrangian (action) of the nonlinear δ model for the pseudogoldstone bosons. The corresponding decay rates are calculated. It is shown that the decay rates are quite large, especially, the rate of the decay W→πγ and probably that of W→ D₀γ are predicted being unexpectedly great (Г_W→πγ = 0.35 GeV). This indicates that the chiral anomalies and our approach should receive tests from SPPS and Tevantron experiments.
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  The Modular Invariant Decomposition of Compact Riemann Surfaces with g > 1

  SHEN Jian-min, XU Kai-wen

  理论物理通讯. 1989, 11(2): 207-214.

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  We show that Jenkins-Strebel quadratic differential theorem can produce a way of decomposition Riemann surface M into ring domains, which keeps modulus invariant. It follows that this kind of partition is related to the triangulation of the moduli space.
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  Hyperon-Neutron Elastic Scattering

  Fazal-e-Aleem, Mohammad Saleem, Muhammad Rafique

  理论物理通讯. 1989, 11(2): 215-220.

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  It is shown that the Chou-Yang model can be extended to hyperon-neutron elastic reactions at high energies by assuming that the hadronic form factor of neutron is proportional to its magnetic form factor. It is also predicted that the scaling of magnetic form factor of neutron with charge as well as magnetic form factors of proton implies that the differential cross sections of corresponding hyperon-proton and hyperon-neutron reactions should be equal.
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  A Disorder Solution for a superlattice GMS Model

  YAO Jian, TANG Kun-fa, HU Jia-zhen

  理论物理通讯. 1989, 11(2): 221-224.

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  A closed form expression for the free energy per site of the triangular superlattice in generalized mixed-spin (GMS) case is obtained by means of the exact decimation approach. A criterion determining the validity of the solution is also given.
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  The Spin-wave Fracton Excitations in Periodic Fractal Structure

  Zi-dan WANG, Chang-de GONG

  理论物理通讯. 1989, 11(2): 225-230.

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  The periodic fractal structure is introduced in this paper. The density of states of a ferromagnetic Heisenberg model on this structure is studied and the basic relation d_s = d_sr + 1 for the spin-fracton dimensionality is derived. Furthermore, the thermal properties on the periodic critical-bond-percolation network within effective-medium approximation (EMA) are discussed.
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  The Tunneling Effect Between Two Weakly Coupled CD W Materials

  Jin-ming DONG

  理论物理通讯. 1989, 11(2): 231-234.

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  Using the tunneling Hamiltonian method we have studied the Josephson type effect occuring in a junction composed of two weakly coupled CDW materials. We have found that the tunneling effect in CDW junction has great resemblance to the Josephson effect, but there are also basic differences between them. For example, in CDW junction there is a special pair-single particle tunneling current term which is absent in the superconducting tunneling junction. It is just this term that gives rise to the narrow band noise. This is a kind of contact effect, but its mechanism is probably different from the vortex theory.
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  A Note on the Pair Excitation Across Major Shell in Deformed Nuclei

  D. H. LU, L. M. YANG

  理论物理通讯. 1989, 11(2): 235-238.

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  Valence nucleons usually play a dominant role in low energy nuclear spectra. The original version of the Interacting Boson Model[1](IBM) with the assumption that all degrees of freedom arise from the valence shell reproduces well large amount of experimental data. However this assumption does not work well in some cases, for instance, in the even isotopes of Sn, Cd, and Hg, Pb rather well developed intruder bands121 lie outside the IBA model space. K. Heyde et al. attributed these low lying intruder states to the pair excitation (PE) across major shell131. In the well deformed nuclei one can hardly think of the closed shell core as being spherical and inert. The rapid change of Nilsson levels with deformation seems to indicate that there should be excitations of nucleons across major shells in the well deformed nuclei.
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  Relativistic Neutrino Spin Precession in Magnetic Fields

  Jiang LIU

  理论物理通讯. 1989, 11(2): 239-242.

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  The spin rotation formula of a relativistic neutrino propagating in a constant magnetic field is derived. Contrary to a recent assertion, we find that in the ultrarelativistic limit, the formula actually reduces to the standard Larmor result.
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  Radiative Correction to Casimir Effect

  She-sheng XUE

  理论物理通讯. 1989, 11(2): 243-248.

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  Radiative correction to Casimir effect is calculated in the U(1).gauge field theory by using Feyman path integral method. The expressions for the radiative correction to the Casimir energy and the Casimir force are given.