1994年, 第21卷, 第2期　
刊出日期：1994-03-15

  

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  A Phenomenological Model on the Superfluid Transition of ⁴He in Porous Media

  X. T. WU, Z. Q. HUANG

  理论物理通讯. 1994, 21(2): 129-134.

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  The superff uid transition of ⁴He in porous media is discussed. The eigenstates of the Hamiltonian may be localized whether the disorder is spatially correlated or not. Based on this argument we proposed a phenomenological model to describe the effects of localization on phase transitions. The system may be divided into many isolated blocks because of the localization. We calculated the superfluid density and the flee energy density for the superfluid transition according to this model. These thermodynamical quantities are described by power Jaws in a certain temperature region but the hyperscaling relation is violated as one can expect. The comparison of the result of this model with the experiment on the superfluid transition of ⁴He in gels is given.
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  Singularities in the Vertex Function in Two-Dimensional Tight-Binding Fermi Systems

  Shi-Min CUI

  理论物理通讯. 1994, 21(2): 135-140.

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  The singularities in the vertex function are studied within the ladder approximation for a non-half-filled two-dimensional tight- binding Fermi system. The location of all the possible poles of the vertex function has been clarified for both repulsive and attractive interacting cases.. The scattering phase shift is examined and found not always zero at Fermi energy. The Kohn-lut tinger-like singularity is also briefly discussed.
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  The Electroabsorption in Quasi-One-Dimensional Halogen-Bridged Mixed-Valence Platinum Complexes

  Jing-Cui PENG, Jian PENG

  理论物理通讯. 1994, 21(2): 141-146.

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  The electroa bsorp tion spectra of the halogen- bridged mixed-valence Pt complexes, [Pt(en)₂][Pt(en)₂X₂] (ClO₄)₄(X = Cl, Br, I) (HMPC's) (en=ethylenediarnine) are calculated using Maxwell equations and dipole approximation, taking into account of the ground state and odd and even charge-transfer (CT) excitons, and only one phonon is involved. The modulation mechanism is quantitatively explained by the electric-field-induced mixing between the odd and the even CT excitons. It agrees with the measured data.
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  Effect of Chemical Potential Shift on Thermodynamical Properties of the Mixed Valence Compounds

  Liang-Bin HU, Tsung-Han LIN

  理论物理通讯. 1994, 21(2): 147-154.

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  Starting from the SU(N_d) Anderson lattice model in the slave boson formalism, we study the effect of the chemical potential shift on the thermodynamic properties of the mixed valence lattice system by using the Green's function technique. In the mean field approximation, the self-consistent equations of the mean field parameters and the chemical potential are obtained. The average number off electrons, the magnetic susceptibility and the specific heat are calculated. The numerical studies show that the shift of the chemical potential has a strong effect on the thermodynamic properties.
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  Wetting Transition of the Maximal Symmetry State in Binary Sullivan Fluid

  Y. SONG, E. J. DING, Z. Q. HUANG

  理论物理通讯. 1994, 21(2): 155-160.

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  The four-phase coexistence state in binary Sullivan fluid mixtures has the maximal symmetry and it is a combination of two two-phase coexisting states of binary Sullivan fluid mixtures. We discuss its wetting transition by making use of the results obtained in two-phase coexistence states directly.
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  Predictions for the Complete Failure of Fibre Bundle

  Yong-Hong WANG, Yan-Nan LU, E-Jiang DING

  理论物理通讯. 1994, 21(2): 161-166.

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  The burst process in a load-carrying bundle of fibres is investigated. The fluctuation of the time for the last failure is studied and proved not to be critical. A new scaling relation D(Δ) ∝ Δ^-1.5 exp(-Δη) near the last failure is obtained analytically. Three methods of the prediction for the last failure are proposed. The method by the first series is applicable only when we do the forecast very near the last failure. The predictions by the exponents in the time windows and by the new scaling relation are feasible for short and long term forecast, respectively.
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  From Braid Group Representations with Four Eigenvalues to Solutions of Yang-Baxter Equation

  You-Quan LI, Lu-Yu WANG, Jun ZHANG

  理论物理通讯. 1994, 21(2): 167-172.

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  A recursive formula of Jimbo-type trigonometric Yang-Baxterization is presented. The consistency conditions of the Yang-Baxterization for four eigenvalues are obtained. Several 4 × 4 solutions of Yang-Baxter equations are obtained from a braid group representation.
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  Quantum Minkowski Space and Generators of Quantum Lorentz Group

  Xing-Chang SONG

  理论物理通讯. 1994, 21(2): 173-180.

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  From the basic 4 × 4 R matrix associated with the quantum Lorentz group SL_q(2, C) and its various fusion matrices, the covariant differential calculus on the quantum Minkowski space and the R commutation relation for the covariant generators of quantum Lorents group are presented.
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  Completeness of the Jost Solutions in the Case of the NLS Equation Under the Nonvanishing Boundary Condition

  Zong-Yun CHEN, Nian-Ning HUANG

  理论物理通讯. 1994, 21(2): 181-186.

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  Completeness of the Jost solutions in the case of the NLS equation under the nonvanishing boundary condition is proved based upon the inverse scattering transform in terms of the auxiliary spectral parameter.
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  The Entire Representation of q-Analogue Coherent, States

  Lei MA, Yong-De ZHANG

  理论物理通讯. 1994, 21(2): 187-192.

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  The en tire represen tation of q-analogue coherent states is established and the expansions for states and operators in this representation are given. Associated with this, a q-analogue of normal ordered operation is defined.
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  An IBM2 Description on the Staggering Phenomenon in the Barium Isotopes

  Yu-Xin LIU, Da-Li ZHANG, Qi-Zhi HAN, En-Guang ZHAO

  理论物理通讯. 1994, 21(2): 193-198.

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  A description on the even-even Barium isotopes for A=128 to 196 and 140 in the framework of neutron-proton interacting boson model is carried out. By introducing the quadrupole interactions among like bosons into the Hamiltonian, the staggering phenomenon in the quasi-γ bands is reproduced pretty well. The physical mechanism behind the improvement is discussed.
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  A Method for Calculating Double Differential Cross Sections of α Particle Emissions

  Jing-Shang ZHANG

  理论物理通讯. 1994, 21(2): 199-204.

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  On the basis of the successful studies on pick-up mechanism of composite particle emission and the angular distribution of single nucleon emissions, a theoretical method for calculating double differential cross sections of α particle emissions is propoLed. As an example, the double differential cross sections of α particles in the neutron induced reaction ⁵⁶Fe(n, xα) have been calculated at E_n = 14.5 MeV. The theoretical results reproduce the experimental data successfully.
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  The Application of Lie Algebra Method in Induced Heavy Nuclei Fission

  Jian-Zhong GU, Yin-Sheng LING

  理论物理通讯. 1994, 21(2): 205-208.

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  The propagator method is efficient in solving the Fokker-Planck equation.with an inharmonic oscillator potential. The propagator is deri;ed by using the Lie algebra method. The fission rate of ²⁴⁰Pu is calculated based on the expression of the propagator. The numerical results show that the rate is reasonable.
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  Pion-Rotational Nucleus Scattering and the Interacting Boson Model

  Yu-Shun ZHANG, Yu-Xin LIU

  理论物理通讯. 1994, 21(2): 209-216.

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  A procedure of combining the medium energy scattering theory in the eikonal approximation with the interacting boson model (IBM) is proposed to study the pion-rotational nucleus scattering. The channel coupling effects in the excitation of nuclear collective state with π^- and π⁺ elastic and inelastic scattering are analyzed. The calculated cross sections for the excitation of 2₁⁺ state of ¹⁵²Sm agmree with the experimental data quite well.
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  Energy-Dependent Potential and Hyperfine Mass Splitting of Quarkonium

  Zhen-Fei LUO, Zhi-Zhan XU, Xi-Jun QIU

  理论物理通讯. 1994, 21(2): 217-222.

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  For scalar and vector interactions, the relativistic two-body Dirac equation is reduced in the nonrelativistic approximation by expanding in powers of E^-1 to obtain energy-dependent effective potentid. The spin-spin part of the resulting potential is applied to analyze the hyperfine mass splitting of quarkonium. It is found that the formula established with such a potential improves the description of hyperfine mass splittings for most ground state and excited state mesons of isospin nonzero and isospin zero.
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  A New Method of Constructing the Functional Integral Directly from Hamiltonian in N (> 2)-Dimensional State space

  Zhong-Can ZHANG, Chong-Sheng LI, Yan-Sheng WE

  理论物理通讯. 1994, 21(2): 223-232.

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  Using the new method of constructing the functional path integral in state space, we accomplished the construction of the functional path integral in N(> 2)-dimensional state space, and illustrated it with the example of n = 3 dimensional case that leads to the same results with others.
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  The Polarization Tensors of Z → 3γ and γγ → γγ via W-Loop in the Standard Model

  Xiang-Dong JIANG, Xian-Jian ZHOU

  理论物理通讯. 1994, 21(2): 233-246.

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  The polarization tensors of Z → 3γ and γγ → γγ W-Boson loops are calculated in the standard model. The constrained equations for the tensors are deduced from the crossing symmetry and gauge invariance. These equations are numerically checked by the polarization tensor of γγ → γγ to the first three lowest orders in its low energy expansion.
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  Gauge Generator in Dirac Theory of Constrained System with Singular High-Order Lagrangian

  Zi-Ping LI, Yi-Cheng XIE

  理论物理通讯. 1994, 21(2): 247-252.

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  A method is proposed for obtaining the canonical equations of motion for a system with the singular 2nd-order Lagrangian (without introducing the Lagrange multipliers). The dependency between the coefficients connecting with the first class constraints in the generator of gauge transformation is obtained clearly. Some confusions in Ref. [9] are corrected. The comparison of our results with others' conclusions is given.
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  A Hopfield Neural Network Model in a Transverse Field

  Yu-Qiang MA, Yue-Ming ZHANG, C. D. GONG

  理论物理通讯. 1994, 21(2): 253-256.

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  A Hopfield model with transverse fields that induce tunneling among neurons is presented. A set of equations for the order parameters describing retrieval and spin glass phases of Hopfield model in a transverse field are obtained without using the tedious replica method, and the memory storage capacity of networks is andysed as a function of the temperatureand transverse field.