1996年, 第25卷, 第4期　
刊出日期：1996-06-15

  

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  Effect of Lattice Quantum Fluctuation on CDW of MX Solids

  Zhi-Gang YU, Yun-Sheng MA, Xin SUN, Y. Takahashi

  理论物理通讯. 1996, 25(4): 385-390.

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  The reduction of charge density wave (CDW) amplitude of MX solids caused by the lattice quantum fluctuation is investigated in a wide range of electron-phonon coupling by using the self-consistent renormalization method. In contrast to polyacetylene, where the bond order wave (BOW) exists well in arbitrary coupling, the effect of the quantum Auctuatipn on CDW of MX solids distinctly depends on the coupling. When the coupling is strol; the reduction of CDW is small; but, if the coupling is weak, CDW is seriously suppressed and even nearly destroyed. This contrast is related to the fact that for weak coupling, the renormalized frequencies of both the acoustic and optical branches are greatly reduced in polyacetylene, but these frequencies in MX solids are not well different from the bare value ω₀.
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  High-Frequency ac Conductivity of Hot Electrons in Bulk Semiconductors

  Z. Q. ZOU, X. L. LEI

  理论物理通讯. 1996, 25(4): 391-396.

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  On the basis of the balance-eq uation transport theory we have carried out a detailed calculation of the small-signal high-frequency conductivity for n-doped bulk GaAs systems under a de bias. Contributions from impurity and phonon scatterings are taken into account. Attention has been paid to the role of electron bulk plasma modes, which give rise to a significant deviation of the high-frequency conductivity from the Drude formula at low dc bias. It is pointed that when the dc bias increases the plasma effect is suppressed by the rise of the electron temperature while the role of the electron temperature oscillation enhances, leading to an appreciable peak in the real part of the conductivity at low frequency.
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  Quantum SK S = 1 Spin Glass with Uniaxial Interactions

  Y. S. XIONG, Y. M. SHANG, L. YI, K. L. YAO

  理论物理通讯. 1996, 25(4): 397-402.

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  The quantum Sherrington-Kirkpatrick (SK) S = 1 spin-glass model with uniaxial anisotropy in applied magnetic field is investigated numerically. The dependences of entropy, specific heat and susceptibility on temperature are calculated for different magnetic fields. The dependence of specific heat on temperature exhibits the typical spin-glass characteristics. It is found that the susceptibility depends strongly on the sign of uniaxial aniso tropy cons tan ts.
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  Photochromism and Photo-Induced Phase Transitions in the Conjugated Polymer Polydiacetylenes

  Jing-Cui PENG

  理论物理通讯. 1996, 25(4): 403-408.

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  A model for describing photochromism and photo-induced phase transition in polydiacetylenes (PDAs) is presented, the lattice deformational energies under photo-excitation are calculated numerically. The mechanism for photo-induced structure phase transition is discussed in detail. It is considered that the excitonic diffusion and relaxation are responsiblefor photochromism and photo-induced structure phase change in PDAs. Based on this model, the experimental results have been explained correctly.
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  Excitation Spectra of λ(φφ⁺)² Relativistic Bose condensate

  Yang ZHANG

  理论物理通讯. 1996, 25(4): 409-414.

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  Using the Bogolu bov transformation method, we calculate excitation energy spectra for a charged relativistic Bose-Einstein condensate with λ(φφ⁺)² interactions. There are two distinct spectra. In the long-wavelength limit one of the spectra approaches to the phonon spectrum for an uncharged nonrelativistic boson condensate, and the other to the nonrelativistic particle energy spectrum. Theground state is explicitly constructed as a coherent state which contains zero-momentum bosons and pairs of quanta with nonzero opposite momenta.
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  Gap Solitons and Resonant Kinks in One-Dimensional Heisenberg Ferromagnets

  Guo-Xiang HUANG

  理论物理通讯. 1996, 25(4): 415-420.

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  Nonlinear excitations in a one-dimensional Heisen berg ferromagnet are studied by a quasidiscreteness approach. The result is valid in the whole Brillourin zone of con tin u um magnon spectrum. We show that the system can support gap solitons at q = 0 and resonant kinks at q = π/d₀, where q is the wave number of the carrier wave and do is the lattice spacing.
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  Topological Classification of the Magnetization States in the Hole-Including Ferromagnets

  Feng-Li YAN, Bo-Zang LI

  理论物理通讯. 1996, 25(4): 421-426.

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  In this paper the problem of topological classification of the magnetization states in the hole-including ferromagnets is comprehensively studied. The main result is that the set of homotopy classes of magnetization states, in a ferromagnet including a family of noninteracting holes of cylinder, sphere and annulus types with numbers m, k and l, respectively, can be constructed into a group isomorphic to z^k+l, the (k + l)-dimensional discrete vector group.
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  Influence of Electric and Magnetic Fields on the Polaron in a Quantum Well

  Shi-Dong LIANG, Chuan-Yu CHEN, Zhuo-He HUANG

  理论物理通讯. 1996, 25(4): 427-434.

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  A combinative method of variational wavefunction and harmonic oscillator operator algebra, the ground-state energy correction to an electron confined in the quantum well of GaAs/Ga_1-xAl_x, As in the electric and magnetic fields along the growth axis has been studied by taking into account the interaction of different optical phonon modes with the electron. The ground-state energy is obtained as a function of the well width and the strength of electric and magnetic fields. The results show that the magnetic field greatly enhances the in terface-phonon part of the polaronic correction to electron ground-state energy in the well width d ≤ 300 Å. The electric field also enhances the polaron effect of interface mode, but decreases the part of bulk longitudinal mode.
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  Exact Propagators for Exciton Motion on a Chain with Alternating Site Energies or Intersite Interactions

  Xian-Geng ZHAO

  理论物理通讯. 1996, 25(4): 435-438.

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  The exciton motion on a chain with alternating site energies (model A) or intersite interactions (model B) is studied analytically. Exact solutions for the amplitude propagators in two systems are obtained explicitly, from which the effects of the site-energy mismatch and the hopping disturbance on the diffusing behavior of the moving exciton are displayed. The symmetry properties for the amplitude propagators in the real space are also given.
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  Hamilton-Jacobi Theory of Colored Noise Problem and Probability Hole in the Bistable System

  Zhi-Gang ZHENG, Gang HU

  理论物理通讯. 1996, 25(4): 439-442.

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  The Hamilton-Jacobi theory in nonpotential systems developed by Maier and Stein is applied to colored noise-driven systems. The behavior of the most probable escape path (MPEP) is discussed. Singularity occurs for the MPEP in the large correlation time τ limit, which is closely related to the well-known probability hole problem. The solution along the MPEP is derived. The behavior near the fixed point is analyzed, and a critical value τ_c, is found, which is in agreement with that obtained by other authors.
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  Thermodynamic Potential in Real-Time Formalisms of Thermal Field Theory

  Hong-Hua XU

  理论物理通讯. 1996, 25(4): 443-446.

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  A full expression for the thermodynamic potential of a given system is derived by the closedtime path approach. It is found with the aid of the residue theorem that this real-form thermodynamic potential coincides with corresponding imaginary one in the Matsu bara formalism. Thermodynamic potential in thermo field dynamics specified by a time-path parameter σ, 0 < σ ≤ β, is also derived and brieffy discussed.
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  (3 + 1)-Dimensional Integrable Models Possessing Infinite Dimensional Virasoro-Type Symmetry Algebra

  Ji LIN

  理论物理通讯. 1996, 25(4): 447-450.

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  Using a series of concrfte reGzations of the centerless Virasoro-type symmetry algebra [σ(ƒ₂(t), σ(ƒ₁(t))] = σ(ƒ₁ƒ₂ - ƒ₂ƒ₁), various (3+1)-dimensional integrable equations under the condition that they possess Kac-Moody-Virasoro-type infinite dimensional symmetry algebra are obtained.
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  Solutions of the Yang-Baxter Equation and Temperley-Lieb Algebraic Structure

  Lu-Yu WANG, Yu CAI, Han-Ying GUO, Shao-Ming FEI

  理论物理通讯. 1996, 25(4): 451-456.

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  The necessary and sufficient condition for the representations of Temperley-Lieb algebra arising from representations of Heck algebra is presented. Using the condition, the representations of braid group with a quadratic reduction relation are divided into two kinds. One has a representation of Temperley-Lieb algebra behind it and another has not. Some concrete examples are discussed with the condition and their Baxterizations are also mentioned.
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  Further Discussion of Effective Quark-Quark Interaction Created by Quark-Antiquark Pair Excitation

  Hong-Shi ZONG, Fan WANG

  理论物理通讯. 1996, 25(4): 457-464.

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  The fourth-order quark-quark potentials in perturbative QCD are derived with special emphasis on the colour-independent spin-orbit-terms, and these terms may be useful in understanding the suppression of the spin-orbit forces in baryons.
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  The Nonlinear Eigenfrequency Shift in QGP

  Xiao-Fei ZHANG, Jia-Rong LI

  理论物理通讯. 1996, 25(4): 465-470.

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  The kinetic equations for quark-gluon plasma (QGP) are studied beyond the linear response theory, and the nonlinear eigenfrequency shift owing to the non-Abelian interaction of the color eigenmodes in a spatially uniform QGP is calculated.
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  Gluonia and Charmonium Decays

  Kuang-Ta CHAO, Yi-Fan GU, S. F. TUAN

  理论物理通讯. 1996, 25(4): 471-478.

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  We discuss the search for a 1^-- gluonium state, 0, in connection with a possible solution for the so-called ρπ, K^*K puzzle in the J/φ and φ' decays. Some issues are examined. In particular, we argue that the expected most favorable process φ → ππO can have an appreciable branching ratio (say 10^-3 ~ 10^-4) only if the O has a very narrow partial decay width to ρπ (say 1 ~ 10 MeV). For the 0^-+ system we deduce a relation that BR(η'_c → h) ≈ BR (η_c → h), where h denotes an exclusive light hadronic channel. This relation may be useful for the experimental search of the yet to be confirmed q: state, for which the branching ratios of φ' → η'_c → γKKπ, γηππ, γη'ππ are estimated to be about 1 × 10^-4 if the mass of η'_c is around 3600 MeV, and this relation may also serve as a criterion to determine whether there exist anomalous decays in the η_c and η'_c system, in particular in the VV decay channels, which might be related to the 0^-+ glueball-charmonium mixing. We emphasize that the bigluonium and the trigluonium may have very different effects on these decays.
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  Phenomenology of χ_F Dependence of Quarkonium Production in Proton-Nucleus interactions

  W. Q. CHAO, C. S. GAO, Y. B. HE

  理论物理通讯. 1996, 25(4): 479-484.

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  We present a phenomenological study of the XF dependence of quarkonium production in high-energy proton-nucleus collisions. The χ_F dependence of comover contributions is introduced to account for the observed quarkonium suppression at low χ_F. Combining comover contributions, nuclear shadowing effect, energy loss mechanism and nuclear absorption together we reproduce the overall χ_F dependence of E772/E789 data.
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  Conservative Angular Momentum as SU(2) Charges in Complex Gravity

  Sze-Shiang FENG, Yi-Shi DUAN

  理论物理通讯. 1996, 25(4): 485-490.

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  We obtain the conservative internal SU(2) charges in terms of Ashtekar new variables from the Lagrangian formalism of complex gravity. It is shown that the charges are related to the conservative angular momentum in the vierbein description of Einstein gravity and the Poisson brackets constitute the SU(2) algebra. Furthermore, they commute with all the constraints hence they are observable and expected to play an important role in the quantization of gravity.
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  The Virialization of a Galaxy in a Dark Halo

  Guo-Rong ZHOU, Shi CHEN

  理论物理通讯. 1996, 25(4): 491-496.

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  The virialization of a mass losing baryonic system in a dark halo is studied for different situations. It has been shown, for a collapsing system, under not very extreme conditions, mass losing may cause dissociation of the system.
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  Weaving of Spherically Symmetric Spaces with Large LOOPS

  Chao-Guang HUANG

  理论物理通讯. 1996, 25(4): 497-500.

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  The weaving of a large class of spherically symmetric spaces with large loops is constructed in the same way as the Zegwaard's construction of weaving of Schwarzchild space. As examples, the weavings of the spatial geometries of Reissner-Nordstrtim metric, Barriola-Vilenkin metric and Lense-Thirring metric are given. The possibility of using this kind of weave to describe the spatial geometry of the Robertson-Walker universe is also discussed.
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  Coherent Motion of Excitons on a Dimerized chain

  Wei-Xian YAN, Wen-Sen LIU, Xian-Geng ZHAO

  理论物理通讯. 1996, 25(4): 501-504.

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  The quantum coherent motion of excitons on a dimerized chain with alternating site energies and in tersite interactions is studied analytically. Exact solutions for the propagators at any site, the mean polarization and mean-square displacement are obtained. Through these exact results and accompanying numerical analysis, it is shown that the increase of the site-energy mismatch and the hopping disturbance will tend to strengthen the localization.
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  A Note on Supersymmetric Two-Boson Equation

  Q. P. LIU

  理论物理通讯. 1996, 25(4): 505-508.

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  We show that the supersymmetric version of two-boson or dispersive water wave system is nothing but one of the N = 2 sKdV systems. We also consider a constrained sKP, which is a gauge equivalence of it.
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  Some Expressions for Legendre Polynomials and Jacobian Polynomials Gained by Virtue of the IWOP Technique

  Hong-Yi FAN, Zhong-Xi ZHANG

  理论物理通讯. 1996, 25(4): 509-512.

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  By virtue of the coherent state and the technique of integration within an ordered product (IWOP) of operators we derive some expressions, which are in differential forms, for Legendre polynomials and Jacobian polynomials.