1989年, 第11卷, 第4期　
刊出日期：1989-06-15

  

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  Probability Evolution and Mean First-Passage Time for Multidimensional Non-Markovian Processes

  WU Da-jin, CAO Li, YANG Bo

  理论物理通讯. 1989, 11(4): 379-388.

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  We investigate a multidimensional system described by a set of stochastic differential equations in which the multiplicative noise is assumed to be an O-U noise. With the help of the projection operator technique, we derive an integrodifferential equation for the probability density and an approximate equation for the mean first-passage time (MFPT).Under some approximation, we obtain an effective Fokker-Planck equation and apply the equation to the single mode laser problem. The concrete calculations of MFPT are made with an important example.
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  Density Correlation Function in a Tunneling Superlattice with Electrons and Holes

  Rui-qing YANG

  理论物理通讯. 1989, 11(4): 389-394.

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  We have studied the electron-electron, electron-hole and the hole-hole density correlation functions of the tunneling superlattice with electrons and holes by using the tight-binding envelope functions and taking account of the nearest-neighbor overlap. Based on a newly developed matrix separation technique, these density correlation functions can be explicitly expressed in terms of a matrix density correlation function which allows for a RPA calculation. An effective matrix screened carrier-carrier potential is introduced, which together with the matrix denmty correlation functions given in this paper provides a convenient way to study excitation, transport, and other propertics of a weak tunneling superlattice with both electrons and holes.
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  Collective Excitations in Quasi-Zero-Dimensional GaAs-Al_1-xGa_xAs Superlattices

  Dan-hong HUANG, Shi-xun ZHOU

  理论物理通讯. 1989, 11(4): 395-400.

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  The linear-respononae theory is used to calculate the dielectric response of tunneling dot superlattice with a simple model including the many-body effect to an external perturbation in a reasonable way. Explicit analytical results for the dispersion relation are derived. The transition behaviour from one-dimensional chain to quasitwo-dimensional tunneling semiconductor superlattice is discussed.
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  A p-d Hybridization Pairing Model in the Cuprates

  SU Gang

  理论物理通讯. 1989, 11(4): 401-409.

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  A new mechanism for the pairing in cuprate superconductors ia proposed and studied by using the mean-field approximations. A hybridieation singlet pair is formed by media of strong hybridization between a d hole on Cu site and a p doped hole with opposite spin on the nearest-neighbor O site in the CuO₂ plane. The transition temperature can be found to reach a peak around δ～0.1-0.3 and the ratio of energy gap to T_c has a maximum 4.0. This is in good agreement with experiments. The specific heat jump as a function of doping fraction δ, the upper critical field and the coherence length, are obtained.
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  Separable Nucleon-Nucleon Potential with Experimental Off-Shell Information

  CHU Lian-yuan, WANG Cui-Ian, LU Ding-hui

  理论物理通讯. 1989, 11(4): 411-420.

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  By means of solving the Lippman-Schwinger equation and Faddeev equation, fitting the two-body and three-body low energy experimental data in a unified way, a set of rank-1 central separable potential is constructed to provide the applications of the nuclear theoretical calculation.
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  Three-Parameter Liquid-Drop Model Describing a Large-Amplitude Collective Nuclear Motion

  BAO Jing-dong, WU Xi-zhen, ZHUO Yi-zhong

  理论物理通讯. 1989, 11(4): 421-431.

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  In this paper, the liquid-drop model with three parameters {c, h,a} is used to describe symmetric or asymmetric fission process. The analytical expression of the effective moment of inertia is given. The inertial and frictional tensors of nucleus are evaluated by the Werner-Wheeler method. Based on a standard liquid-drop model, the Coulomb energy and surface energy are accurately calculated. The scission point of the fissioning nucleus is defined by energy criteria. The salient features of the dynamical coefficients are discussed.
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  A New Method for Calculating the Double Beta Decay Probability

  CHING Cheng-rui, HO Tso-hsiu

  理论物理通讯. 1989, 11(4): 433-440.

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  A new method of calculating 2υ-2β decay probability ia derived. It is shown that with the present knowledge of nucleon-nucleon force and reasonable nuclear wave functions for the parent and daughter nuclei this method can provide a reliable result without using closure approximation.
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  A Recurrent Formula for Fractional Parentage Coefficients of Identical Fesmions

  Hong-zhou SUN, Qi-shi HAN, Mei ZHANG, Gui-lu LONG

  理论物理通讯. 1989, 11(4): 441-447.

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  A recurrent formula of fractional parentage coefficients (CFPs) with explicit senioritiea for identical fermions in the j-j coupling acheme is given. The multiplicity of statee with fixed seniority and angular momentum is also given. Using irreducible tensor method, the CFPs are factorized completely along a group chain. It is found that the CFPs are directly related to the group reduction coefficients. Them are useful for constructing an efacient iteration method of calculating the CFPs.
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  The Fractional Parentage Coefficients for a Double-j Fermion System

  Hong-zhou SUN, Qi-zhi HAN, Mei ZHANG, Gui-lu LONG

  理论物理通讯. 1989, 11(4): 449-457.

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  The coefficients of fractional parentage (CFPs) for a double-j fermion system are defined. The CFPs are given when the wave functions are classified according to the group chains U(N) ⊃ U(N₁) × U(N₂) ⊃ SP(N₁)× SP(N₂) ⊃O(3₁)×O(3₂) ⊃ O(3) and U(N) ⊃ SP(N) ⊃ SP(N₁)× SP(N₂) ⊃ O(3₁)× O(3₂) ⊃ O(3). Using these CFPs many repeating calculations can be avoided.
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  Amplitudes for the Bosonic String with Boundaries

  CHANG Zhe

  理论物理通讯. 1989, 11(4): 459-466.

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  We deal with the problem of the computation of amplitudes for the bosonic Polyakov string with boundaries and show that both conformal invariance and reparametrisation invariance are maintained in critical dimensional d = 26 as the case without boundaries. The amplitudes of the bosonic, closed oriented Polyakov string with boundaries are formulated aa integral over moduli space with respect to the Weil-Petersson measure.
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  Eigenstates of Electromagnetic Field in the Presence of External Source

  BI Yong-yi, FAN Hong-yi

  理论物理通讯. 1989, 11(4): 467-478.

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  We study electromagnetic field theory in the presence of external source and show how eigenstates of electromagnetic field are related to the external source. With the help of coherent state and functional integral techniques, we derive explicit expressions of the eigenstates.
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  Non-Perturbative Corrections to the Bound State Equation in QCD

  Tao HUANG, Zheng HUANG

  理论物理通讯. 1989, 11(4): 479-488.

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  We have taken into account non-partnrbative correctios to the bound atate equation in the effective QCD theory. The Betha-Salpeter equation for the light mesons is solved in the zero-order, approximation, where only gluon condensate is considered. The results are quite reasonable.
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  A Reduced System of Linear Algebraic Equations for Giving Soliton Solutions of the Generalized ZS/AKNS Systems

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

  理论物理通讯. 1989, 11(4): 489-494.

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  A simple method for finding soliton solutions of the generaked ZS/AKNS systems whose Lax pairs are matrices with high orders is considered. An explicit expreesion of transformation between the Jost solution relating to the (n-1)-soliton solution and that relating to the n-soliton solution is found. A reduced system of N algebraic equations for giving N soliton solutions is deduced, it has an identical form no matter how high the order of matrices of the Lax pain is.
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  A Discussion of the Question in Connexion with the Expansion of a Divergent Series Encountered in Calculating Nuclear 2υ-2β Decay Matrix Element

  C.R. CHING, T.H. HO

  理论物理通讯. 1989, 11(4): 495-497.

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  It is shown that the expansion and summation of the divergent series occurring in 2υ-2β decay calculation^[1,2] can be well-defined without mathematical flaw.
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  Some Possible Asymmetry Effects of Nuclear Matter in Relativistic Heavy Ion Collisions

  Kai Cheong CHUNG, Cheng-shing WANG

  理论物理通讯. 1989, 11(4): 499-504.

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  The asymmetry dependence of nuclear incompraeaibility and that of nuclear critical temperature are calculated baaed on a Thomas-Fermi model with Seyler-Blanchard interaction. It is found that the asymmetry effects are big enough to allow for checking the existence of these effects in relativistic heavy-ion collision experiments.
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  A New Correction Term in Nuclear Neutrinoless Double Beta Decay

  CHING Cheng-rui, HO Tso-hsiu

  理论物理通讯. 1989, 11(4): 505-508.

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  Using a new method described in Ref.[1], it is shown that for nuclear neutrinoless double beta decay in 2n mechanism, there appears a new correction term, which is absent in the conventional treatment based upon the closure approximation.
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  A Generalized Jaynes-Cummings Model for Two Collectively Radiating Atoms

  FAN Hong-yi

  理论物理通讯. 1989, 11(4): 509-513.

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  The Jaynes-Cummings model in theoretically generalized to the simplest case of collectively radiating atoms. The comsponding Hamiltonian is diagonalked and some transition process in calculated.