1989年, 第12卷, 第3期　
刊出日期：1989-10-30

  

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  High Field Balance Equations of Quantum Wire Structures

  CAI Jian

  理论物理通讯. 1989, 12(3): 249-262.

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  Balance equations are established for steady-state nonlinear electronic transport in the presence of an electric field both for a single quasi 1D-heterostructure and for a multi-quantum-wire superlattice. The carrier-impurity scatterings and carrierphonon scatterings have been taken into account. The general equations for determining the resistivities are obtained and the Ohmic mobility formula are given. The density-density correlation functions for the wire structures are also studied in some detail.
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  Off-Diagonal Long-Range Order (ODLRO) Solitons and Superconductivity

  He-shan SONG, AN Ing, Xue-qian LI

  理论物理通讯. 1989, 12(3): 263-272.

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  The analogue between monopole-fermion interaction in the spontaneously broken gauge theory and phonon-electron interaction in the theory of superconductivity is studied. It is shown that both monopole-fermion interaction and phonon-electron interaction are characterized by the existence of the off-diagonal long-range order. Starting from the analogue between monopole-fermion interaction and phononelectron interaction the possible relevance of condensed solitons to superconductivity is also discussed.
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  A Trial of Variational-Cumulant Expansion on Simple Ising Model With Second Order Phase Transition

  CHE Hao, XIA Yu, WANG Hong-mo, SONG Yong-xin

  理论物理通讯. 1989, 12(3): 273-289.

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  The standard variational-cumulant expansion (VC) combined with a scheme for the enumeration of connected diagrams is employed to study the simple Ising model with the second-order phase transition. This model is evaluated to the 5th order approximations. A comparison with the 2-dimensional exact results shows that thermodynamic quantities converge rather slowly to the exact values in the intermediate region. A strict analytical calculation of the critical temperature with the 5th order approxinlation both for J_i and cumulant expansion suggests that VC chn achieve rather high standard accuracy if the variational parameters J_i could be determined up to higher degrees of corrections rather than the first one. Anomalies are found for U, C and M at extremely low temperature. A detailed study of M implies that thermodynamic formulae should be carefully chosen in VC approach so as to avoid these anomalies.
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  Low-Energy Exciton-Model Limit for the Gamma Emission

  E. Běták

  理论物理通讯. 1989, 12(3): 291-298.

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  The pre-equilibrium exciton model of the gamma emission is considered in its lowenergy limit. The basic ingredients of the picture are essentially the same as at more advanced energies; however, a straightforward reduction of the equations to simple formulae, what was the case of higher energies, does not take place here. The influence of the Pauli blocking principle is more significant for the low energies than for the standard energies. Anyway, the manifestation of the pre-equilibrium character in the calculated spectra is highly masked by the equilibrium component, so that one cannot clearly distinguish among the models used.
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  The Relation Between K⁺/π⁺ Ratio and Secondary Collisions in Ultra-Relativistic Heavy Ion Collisions

  REN Jiang-long, CHAO Wei-qin

  理论物理通讯. 1989, 12(3): 299-302.

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  Based on the concep, t of the formation time, the contribution of secondary collisions to the change of the K⁺/π⁺ ratio in ultra-relativistic heavy ion collisions is calculated. The result shows that the effect of secondary collisions in the target nucleus is not enough to explain the observed change of the K⁺/π⁺ ratio.
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  Definite Integral Expression of the SU(3) One-Link Integral

  LIU Jin-ming, GONG Di

  理论物理通讯. 1989, 12(3): 303-309.

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  A definite integral expression of the SU(3) one-link partition function invariant group integral in the weak coupling regions of lattice gauge theories is obtained by the steepest descent meth.od. The integral can be numerically evaluated easily. This method can be extended to evaluation of some related SU(3) group integrals in the lattice gauge theories.
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  Monte Carlo Study of 3-d Z₄ Gauge-Z₂ Higgs Theory with Radial Degree of Freedom

  ZHU Yun-lun

  理论物理通讯. 1989, 12(3): 311-325.

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  Phase structure of the 3-d lattice Z₄ gauge-Z₂ Higgs theory is investigated by the Monte Carlo simulation. We find a new phase, named Higgs Ⅱ phaae, when λ (scalar self-coupling constant) is small. It is a result of the radial excitation of Higgs field.
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  Explicit N-Soliton solutions in the Inverse Scattering Method

  CHEN Zong-yun, HUANG Nian-ning, XIAO Yi

  理论物理通讯. 1989, 12(3): 327-332.

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  By using the technique of determinant calculation, explicit N-soliton solutions of the Korteweg-de Vries equation and the nonlihear Schrödinger equation are obtained for arbitrary N in terms of the inverse scattering method. Therefore, the relations of the inverse scattering method with the direct method of Hirota become easy to be understood.
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  Double-Chain Mean-Field Renormalizat ion Group Approach for the Ising Model

  Zhu-pei SHI, Rui-bao TAO

  理论物理通讯. 1989, 12(3): 333-336.

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  A double-chain mean-field renormalization group approach for the Ising model is formulated. With the approach, transition temperatures and critical exponents for several numbers of nearest-neighbor chains are obtained.
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  RVB-Itinerant P Hole Model for High-T_c Copper Oxides

  WU Hang-sheng, SU Zhao-bin

  理论物理通讯. 1989, 12(3): 337-340.

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  A model for the high-T_c Copper Oxides is studied. The, localized nature of Cu 3d electrons is described as the RVB quantum spin liquid and the doped O 2p holes are described with an itinerant band. Our analysis shows that the virtual exchange of two spinons induces a pairing interaction between two holes.
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  Wave Function of Contract-Expanding Universe

  Hao-gang DING, Han-ying GUO, Wei-liang SHEN

  理论物理通讯. 1989, 12(3): 341-344.

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  It is shown that the wave functions of a contract-reexpanding universe may be constructed in two different ways corresponding to different boundary conditions in superspace and both may offer satisfactory inflationary scenario.
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  The Coherent Tunnelling with Position-Dependent Mass in a Bistable Potential

  Sen-yue LOU, Guang-jiong NI

  理论物理通讯. 1989, 12(3): 345-348.

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  A particle with position-dependent mass moving in a double well potential is investigated. An exact instanton solution is given and tunnelling effect caused by it is considered. We calculate the energy of the ground state of this model by introducing some effective mass and frequency of oscillator.
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  The Algebras of Meromorphic Vector Fields and the Bases of Meromorphic λ-Differentials on Riemann Surfaces

  Han-ying GUO, Ji-sheng NA, Jian-min SHEN, Shi-kun WANG, Qi-huang YU

  理论物理通讯. 1989, 12(3): 349-354.

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  The algebras of meromorphic vector fields and the bases of meromorphic λ-differentials with multipoles are constructed explicitly on general genus Riemann surfaces. For Riemann sphere the central extension of the algebra is also given.