1990年, 第13卷, 第2期　
刊出日期：1990-03-15

  

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  Probability Density and Joint Probability Density of SDE with General Nonlinear Gaussian Noise

  LIU Zhong-hua, CHEN Li-hua, ZHU You-xing

  理论物理通讯. 1990, 13(2): 135-146.

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  We consider a stochastic differential equation with a general nonlinearity in Gaussian noise; With both D (fluctuation intensity) and γ (correlation time) small quantities with D/γ < 1/10, approximate equations for the probability density p(q, t) and the joint probability density p(q, t, q^t, t^p) are derived. As applications of our general equations, quadratic noise, exponential noise and triangle function noise are studied.
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  Theoretical Calculation of the Eutectic Point for 27 Binary Alkali Halide Systems Having Common Ions

  CHEN Li-rong

  理论物理通讯. 1990, 13(2): 147-152.

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  We suppose that the excess enthalpy and entropy may be expanded as polynomials in the mole fractions, and determine the equations of the liquid-solid phase equilibrium curves of a binary system according to thermodynamic theory. For the 27 binary alkali halide systems having the phase diagram with an eutectic point, we calculate the values of the eutectic point (T_o, X_Bo). These results agree well with the experimental values.
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  Nonlocal Ginzburg-Landau Equations

  Hong-hua XU, Chien-hua TSAI

  理论物理通讯. 1990, 13(2): 153-166.

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  Real time Gor'kov equations and the accompanying electric current expression in terms of the retarded Green's functions are established at finite temperatures with the aid of the Closed-Time-Path-Green's-Function formalism. The fluctuation-dissipation theorem then helps us to obtain nonlocal G-L equations near T_c which reduces to the conventional G-L equations in the local limit. The kernel containing nonlocal effects in our equations has an asymptotic behavior k^-2 for k → ∞ and is, therefore, quite different from the BCS kernel. This novel kernel leads naturally to reversal of the magnetic field in the neighborhood of a vortex in type Ⅱ/1 superconductors.
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  Nonlinear Electronic Transport Equations for Tunneling Superlattices

  R.Q. YANG, X.L.LEI, C.H. TSAI

  理论物理通讯. 1990, 13(2): 167-172.

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  We present a nonlinear electronic transport theory for a tunneling superlattice which is composed of interacting electrons with impurity and phonon scatterings. The theory is based on the Lei-Ting balance-equation method and a newly developed matrix separation technique for the density-correlation-function. Taking account of the overlap of the wave-functions between adjacent wells, the nonlinear dc resistivity in a transverse strong electric field is explicitly expressed in terms of the matrixdensity- correlation-function, which can be straightforwardly calculated in RPA as long as the single well wave function is given.
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  Balance Equation Approach to Nonlinear Polaronic Transport

  J.CAI, X.L.LEI

  理论物理通讯. 1990, 13(2): 173-180.

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  Balance equations beyond the lowest order perturbation expansion for high-field electronic transport are developed and used to discuss the polaronic resistivity in polar semiconductors and other systems. Significant corrections in the case of high electric field are expected.
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  Clebsch-Gordan Coefficients, Racah Coefficients and Braiding Fusion of Quantum sl(2) Enveloping Algebra (I)

  Bo-yu HOU, Bo-yuan HOU, Zhong-qi MA

  理论物理通讯. 1990, 13(2): 181-198.

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  Quantum Clebsch-Gordan coefficients and the first type quantum Racah coefficients of quantum sl(2) enveloping algebra are given explicitly. The quantum 3-j and 6-j symbols, similar to those in the theory of angular momentum are abo introduced. The solution R_q^j1j2 of quantum Yang-Baxter equaton is expressed in terms of the quantum Clebsch-Gordan coefficients. It is shown that when j1=j2, R_q^jj is just the same as R_AW^j matrix obtained by Akutsu and Wadati for the representation of the braid group. The second type quantum Racah coefficients, which are the solutions of the face models, are also computed explicitly and related to the first type quantum Racah coefficients. The famous pentagonal relation is proved from the formula between two quantum Racah coefficients. The graphical representation of those formulas is discussed.
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  Electromagnetic Gauge Invariance of Bound State Annihilation Amplitudes

  ZHENG Han-qing

  理论物理通讯. 1990, 13(2): 199-208.

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  Gauge invariance of the electromagnetic vertex of bound state annihilation matrix elements is demonstrated by using Ward identities and Dyson equations. This problem is also discussed when potential assumption of the B-S kernel and the approximation of neglecting photon lines hung on closed fermion loop are considered. Under these two approximations, the simplified matrix element expression is given, which preserves the gauge invariance. The reliability of using zero point wave function approximation in cc, bb system is also discussed.
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  Irreducible Representations of Quantum sl(3) Enveloping Algebra

  LIAO Li, SONG Xing-chang

  理论物理通讯. 1990, 13(2): 209-216.

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  By referring to the construction method of finding representations of classical U(n) group, we developed a parallel method with which one can construct irreducible representations of quantum sl(3) enveloping algebra explicitly.
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  Boson Realization of Representations for Quantum Groups and Its Differential Correspondence in Bargmann Space

  Chang-pu SUN, Hong-chen FU

  理论物理通讯. 1990, 13(2): 217-226.

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  By constructing the q-analogue of the Heisenberg-Weyl algebra in terms of usual creation and annihilation operators of boson states in the Fock space, the boson realization method recently suggested^[7-11] is generalized to obtain a class of representations of quantum group in the Fock space. The q-deformed differential realization of quantum groups proposed by Alvarez-Gaume is derived by making use of the boson realization in this paper.
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  Anomalous Vector-Boson Mass Generation on a Lattice

  Zhong-shui MA, Shuo-hong GU0

  理论物理通讯. 1990, 13(2): 227-236.

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  We show the vector boson mass generation on a lattice with the Wilson's fermion formulation. By calculating explicitly the change of the effective action under chiral transformation, it is also found an arbitrariness in the solution of the chiral Schwinger model, which depends on a lattice regularization in continuum theory.
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  A Self-Damping Phenomenon in the Motion of the Soliton

  JIANG Shao-zhou

  理论物理通讯. 1990, 13(2): 237-240.

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  The properties of the soliton's acceleration in a constant applied field are studied numerically. The results indicate that its acceleration varies in waves rather than maintains constant in time, and it is not proportional to the applied field. The motion of the soliton appears to be a self-damping phenomenon.
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  The Self-Trapping Energies of a Magnetopoloron in a Polar-Crystal Slab at Finite Temperatures

  Bao-hua WEI, Shi-wei GU

  理论物理通讯. 1990, 13(2): 241-245.

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  Taking into account the interaction of an electron with both bulk longitudinal-optical (BO) and surface-optical (SO) phonons, the temperature dependence of the selftrapping energies of a magnetopoloron in a polar-crystal slab in arbitrary magnetic field strengths is investigated by using the generalized Larsen perturbation-theory method.
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  An Interface Magnetopoloron in Arbitrary Magnetic Field Strength at Finite Temperatures

  Bao-hua WEI, Shi-wei GU

  理论物理通讯. 1990, 13(2): 247-250.

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  Taking into account the interaction of an electron with both LO and IO phonons, the magnetic field and temperature dependence of the pfoperties of an interface magnetopoloron is investigated. The results show that the temperature dependence of the properties of interface magnetopolaron depends strongly on the magnetic field strength. The results also show the important role played by the electron-IO phonon interaction.
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  SU(6) Analysis of Mesonic of B-Mesons

  Dan-di WU

  理论物理通讯. 1990, 13(2): 251-256.

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  The SU(6) symmetry of strong interactions among light quarks is used to analyse two-body mesonic decays of B-mesons based on the Hamiltonian proposed by He-McKellar- Wu.
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  Can Natural Flavor Conservation Coexist with CP Violation Mixing Matrix in Multi-Higgs Scalar Models?

  Dong Fang Xiao

  理论物理通讯. 1990, 13(2): 257-260.

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  A class of multi-Higgs scalar four-family SU(2)×U(1) models is discussed in which tree-level NFC, SCPV and a CP violation mixing matrix coexist together.
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  Comments on a Definition of Maximal CP Violation

  ZHANG Zhi-qing, WU Dan-di, HUANG Tao

  理论物理通讯. 1990, 13(2): 261-266.

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  In the weak basis with diagonalized up quark mass matrix and Hermitian down quark mass matrix, the sequential product of the off dingonal elements M₁₂^dM₂₃^dM₃₁^d is a phase-convention-independent quantity. The idea of using the argument of this product to define maximal CP violation is examined, along with other definitions. The argument in reality is not π/2 allowing experimental and theoretical uncertainties.
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  Wormholes and Non-Linear σ Models

  Jia-ru WEN, Han-qing ZHENG

  理论物理通讯. 1990, 13(2): 267-270.

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  We show that the Giddings-Strominger-like wormholes exist in the systems comprised of SU_L(n)×SU_R(n) or O(n) non-linear a models coupled to O(4) symmetric gravity. Some details are discussed for the case of SU_L(2)×SU_R(2) and two kinds of wormhole instantons are shown.