1992年, 第18卷, 第3期　
刊出日期：1992-10-30

  

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  Details of Electron-Electron Correlation of P^e Helium States by Partial-Wave Analysis

  Y.W. DUAN, C.G. BAO

  理论物理通讯. 1992, 18(3): 257-264.

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  The N = 2 and N = 3 series of the ¹P^e doubly excited helium states are investigated by a partial-wave analysis, and by inspecting the one-body densities and the shape-densities. Many features in the anisotropism of the electronic cloud, in the geometric configuration, and in the details of radial-radial correlation are found. A comparison between the ²P^e and ³P^e states is made.
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  Dynamical Behaviour of the Bonhoeffer-van der Pol Model

  Wei WANG, Xi-Xian YAO

  理论物理通讯. 1992, 18(3): 265-274.

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  The dynamical behaviour and the threshold phenomenon for the Bonhoeffer-van der Pol model of a nerve membrane stimulated by a constant and a periodic currents are investigated. For the constant current lo, there are two Hopf bifurcations at I₀ = I_L and I₀ = I_H, respectively. At I₀ = I_L an infinite long train of nerve impulses (threshold phenomenon) is found. For the periodic current, there are an ordinary period-dou bling to chaotic state, and a mode-locking state, as well as a reversed period-doubling from chaotic state to period-1 state. A phase diagram for the threshold phenomenon in the parameter space (I₁ and ω, amplit ude and frequency) is obtained. In our discussion we conclude that the period-n oscillations correspond to the n-shaped impulse trains, and the chaotic oscillation corresponds to the infinite-shaped impulse trains. All of these impulses of the BVP model system code the information process of the nerve fibre in neural tissue.
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  Motion of a Charged Particle in an Arbitrary Time-Dependent Electric Field with Alternating Intersite Interactions

  Xian-Geng ZHAO

  理论物理通讯. 1992, 18(3): 275-282.

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  The motion of a charged particle on a linear chain under the action of an electric field with alternating intersi te interactions is investigated. Exact solutions for the Wannier state amplitudes, the propagators and the mean square displacement are obtained for the general case of an arbitrary time-dependent electric field, of which a dc+ac electric field is only a special one. The dynamic localization condition is given for this special case. This condition would make the observation of dynamic localization effect possible.
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  The Transition Temperature for Metal-Oxide Super-conductors YB₂Cu₃O_7-δ on the Basis of Three Overlapping Energy Bands Theory

  Zhi-Xing WANG, Xi-Fu WANG

  理论物理通讯. 1992, 18(3): 283-286.

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  It is shown that the consideration of three energy bands overlapping on the Fermi surface allows to calculate the superconducting transition temperature dependence on the chemical potential of YB₂Cu₃O_7-δ.
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  Haldane Gap in One-Dimensional Spin Chains

  Su-Qing CHEN, Guang-Jiong NI, Ping SUN

  理论物理通讯. 1992, 18(3): 287-292.

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  One-dimensional antiferromagnetic spin chains (S = 1) are quantized by means of the Gaus sian effective potential method for the O(3) nonlinear a model. The critical line-separating the missive phase with Haldane gap and massless phase is found in an analytic form. The spin correlation function is discussed via the sine-Gordon formulation as well.
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  Joint Probability Distribution of the System Driven by Internal and External Noises Simultaneously

  Li-Hua CHEN, Ya JIA

  理论物理通讯. 1992, 18(3): 293-298.

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  We obtain the equation for the steady state joint probability distribution of the system driven by external and internal noises simultaneously, where external noise is the dichotomous noise and internal noise is the Gaussian white noise. As to the application of our equation, we discuss two examples for which the correlation functions and associated relaxation times are calculated. We find the coupling effect of the external and the internal noises for the relaxation time.
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  A Semiclassical Theory of Multistep Nuclear Reaction Processes

  Jing-Shang ZHANG

  理论物理通讯. 1992, 18(3): 299-306.

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  The master equation theory of precompound and compound nuclear reactions has been generalized with inclusion of the conservation of angular momentum and parity. This improved semiclassical theory has been extended for application as an evaluation tool of the calculations of nucleon induced reaction cross sections and double differential cross sections. For structural materials at incident neutron energies below 20 MeV, it is demonstrated that the constructed model contains the Hauser-Feshbach, Weisskopf-Ewing as well as the exciton models as limiting cases. The unified treatment ofpre-equilibrium processes includes a number of interesting features, such as the exciton state densities with the exact Pauli exclusion correction which are renormalized to the back-shifted Fermi-gas formula, the introduction of formation factors of composite particle in calculations of pick-up type composite particle emission and the double differential cross sections (DDCS) for all kinds of particles in terms of the leading particle model.
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  Mass of Light Neutrino and Right-Handed Current in ⁷⁶Ge and ⁸²Se 0vββ Decays

  C.L. SON, H.F. WU

  理论物理通讯. 1992, 18(3): 307-312.

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  We discuss the Ovββ decay mediated by a light neutrino. Two-nucleon mechanism and shellmodel wave function are used in this paper. Also we take into account the influences of both nuclear short-range correlation term and finite nucleon size on the calculations of transition matrix elements. The relation between the mixing parameter η of right-handed current and the Majorana neutrino mass mv is obtained by fitting the experimental dtlta of Ovββ decay lifetimes of ⁷⁶Ge and ⁸²Se.
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  The Effect of Bare Quark Mass on the Pion Properties in BS Formalism Containing a Confining Term

  Yuan-Ben DAI, Yi-Bing DING, Chao-Shang HUANG, Chui-Lin WANG

  理论物理通讯. 1992, 18(3): 313-320.

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  Using the SD equation and the covariant BS equation, we investigate dynamical chiral symmetry breaking in the presence of a bare quark mass in a QCD motivated model containing a confining interaction. The bare quark mass m₀ corresponding to the physical mass of the pion and corrections to the dynamical quark mass and the pion decay constant due to mo are calculated. The results are consistent with the notion of chiral perturbatiyn and predictions of the current algebra.
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  Possible Phenomenological Indication for the String Coulomb Term and the Color Screening Effects in the Quark-Antiquark potential

  Kuang-Ta CHA0, Yi-Bing DING, Dan-Hua QIN

  理论物理通讯. 1992, 18(3): 321-326.

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  The string Coulomb term in the quark-antiquark potential which is due to the transverse. vibrations of the flux tube in the string picture is discussed. Possible phenomenological indication evidences for this term and the color screening effects are studied by examining its spin-dependent effects on both the fine and hyperfine splittings of the P wave charmonium states.
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  Relativistic Equation Represented in Pauli Spinor Space for Two-Fermion Scattering States

  Jun-Chen SU

  理论物理通讯. 1992, 18(3): 327-336.

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  The Bethe-Salpeter equation for two-ferrnion scattering states is reduced to an equivalent Pauli-Schriidinger equation. The latter equation provides a new approach to the relativistic scct tering problem. Since this equation may avoid the problem of solving coupled equations, it appears to be more convenient than the Bethe-Salpeter equation in practical applications.
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  Conservation Laws and Bianchi Identities in R+R²+Q² Theories

  Yuan Zhong ZHANG

  理论物理通讯. 1992, 18(3): 337-342.

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  We investigate the conscrvalion Jaws in the class of R+R²+Q² theory with torsion. We prove that the conservation Jaws may be dcrived Born the Bianchi identities of the curvature and torsion tensors. In particular the conservation law for matter is showed to be a result of the Dianchi identities and gravitational ficld equations just as it does for T^uv=0 in general relativity.
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  Simple Approach for Deriving the Weyl Correspondence Product Formula

  Hong-Yi FAN, Hai-Guang WENG

  理论物理通讯. 1992, 18(3): 343-346.

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  By making use of the coherent state representation of the Wigner operator we present a simple approach for deriving the Weyl correspondence product formula in complex phase space. The formula tells us how to express the Weyl classical function corresponding to an operator F = AB in terms of the Weyl functions corresponding to A and B.
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  Mass Inequalities in Vectorial Gauge.Theory Based on Compact Semi-simple Lie Group

  Bang-Rong ZHOU

  理论物理通讯. 1992, 18(3): 347-352.

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  The mass inequalities valid in the vectorial gauge theory based on a simple group can be generalized to the case with a compact semi-simple Lie group if the vacuum angle is assumed to be zero. A new meaning of these inequalities lies in that a vectorial Aavor gauge symmetry can not be spontaneously broken by the color condensates among the fermions with nonzero bare masses. In the semi-simple group case the vacuum angle could be naturally set to be zero only if there are massless fermions assigned in special representations of the group. This provides the possibility to break down the mass inequalities and could find some physical applications.
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  Chern-Simons Gauge Theory and Ginzburg-Landau Type Theories (Ⅱ) Non-Abelian Cases

  He-Shan SONG, Shu-Xue DING, Ing AN

  理论物理通讯. 1992, 18(3): 353-356.

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  It is shown that after the Higgs mechanism takes place, the gauge field A, in non-Abelian Higgs models (whatever with or without Chern-Simons term) follows the same field equation with massive non-Abelian Chern-Simons gauge theory and hence admits the same particlelike solutions.
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  Approximate Method for Nielsen-Olesen Vortices

  Qiong-Gui LIN, Guang-Jiong NI

  理论物理通讯. 1992, 18(3): 357-362.

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  We propose a simple approximate method for the Nielsen-Olesen vortices. The energy and the core size of the vortex are obtained. A conserved topological current and its charge are constructed.
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  Strongly Diluted Neural Networks with Correlation-Causing Stimuli

  Ye-Gao XIAO, Harald ENGLISCH, Kai-Lun YAO

  理论物理通讯. 1992, 18(3): 363-368.

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  The strongly diluted neural networks are studied rigorously under correlation-causing stimuli for any time step with a Gaussian distribution of stabilities. For the second time step, the analytical formulas of retrieval qualities are derived by taking the correlation between random variables into consideration. Numerical results show that the correlation deteriorates the improvement of the retrieval quality by persistent stimuli in comparison with the case neglecting it, but it is, at least for t = 2, not strong enough to cause essential discrepancy between the retrieval qualities for the networks with non-correlation- and correlation-causing stimuli respectively.
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  Finite Dimensional Representations of Braid Groups

  Zhong-Qi MA, Dian-Min TONG, Bin ZHOU

  理论物理通讯. 1992, 18(3): 369-372.

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  In this letter the general forms of the finite dimensional representations of braid groups are obtained. The equivalent conditions and the irreducibility of the representations are also discussed.
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  The q-Boson Realizationo f Parametrized Cyclic Representations of Quantum Superalgebra

  Hong-Chen FU, Mo-Lin GE

  理论物理通讯. 1992, 18(3): 373-378.

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  By constructing a parametrized cyclic (PC) representation of the q-deformed Heisenberg-Weyl algebras the PC.represen tations of quan tum superalgebra U_qosp(l, 2n) are studied in terms of its q-boson realization. A new type of PC representations of the rank-1 quantum superalgebra U_qosp(l, 2) is obtained by this way.
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  Link Polynomials and Hamiltonian Corresponding to Braid Group Representations of Z_N Model

  Hong-Kang ZHAO, Mo-Lin GE

  理论物理通讯. 1992, 18(3): 379-384.

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  The more general braid group representations of ZZ_N model are given. Topologically invari-ant link polynomials related to the model are constructed. Here we present the simplest Hamiltonian with arbitrary coefficients of 1D quantum chain.