1997年, 第27卷, 第4期　
刊出日期：1997-06-15

  

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  Study of Nonclassical Features and Quantum Dynamics in the Jaynes-Cummings Model

  Rui-Hua XIE, Gong-Ou XU, Dun-Huan LIU

  理论物理通讯. 1997, 27(4): 385-394.

  摘要 ( 376 ) PDF全文 ( 700 )   可视化   收藏

  Some nonclassical features, including photon antibunching, atomic squeezing and quantum collapse-revival phenomenon, were numerically studied in thp vacuum field Jaynes-Cummings model (JCM). The influence of the initial atomic coherence on these features was discussed. It is shown that the squeezing can appear only if the atom is initiaJly prepared in the coherent state, and photon antibunching cHn occur if the atom is initially in the excited state or the coherent one. The effect of the virtual-photon field was studied in JCM without the rotating-wave approximation (ftWA). We have shown that even undh the condition in which RWA is considered to be valid, there are significant effects on the nonc1assical features due to the interference between the virtual-photon processes and the real-photon processes. Quantum dynamics of JCM without RWA was aJso studied. We showed that regular dynamical behavior is exhibited in the cases rather close to the integrable limits, and irregular dynamical behavior is presented in the cases far from the integrable limits; in addition, all the nondassical features disappear in the cases far from the integrable limits.
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  Many-Particle Problems of Thermal Conduction in Two Dimensions

  Guo-Qing GU, Kin-Wah YU

  理论物理通讯. 1997, 27(4): 395-402.

  摘要 ( 431 ) PDF全文 ( 591 )   可视化   收藏

  A general scheme is developed to solve many-particle problems of thermal conduction in two dimensions. Based on the Green's function formalism, heat sources induced by discontinuity of temperature fields and temperature potentials on inclusion boundaries are explicitly taken into account, and analytical expressions for temperature distributions in granular systems are established. The unknown coefficients in the analytical expressions for temperature field are determined by a matrix equation whose elements are all monomials of the distances between particle centers. Decomposition of the matrix equation for the systems containing a chain of particles is discussed. Illustrative calculations are presented for granular systems with two and three particles.
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  Nonlinear Susceptibility of Strongly Nonlinear composites

  Lei GAO, Jia-Jun WANG, Zhen-Ya LI

  理论物理通讯. 1997, 27(4): 403-406.

  摘要 ( 387 ) PDF全文 ( 459 )   可视化   收藏

  By means of a variational approach, we study the effective response of strongly nonlinear composite media with a low concentration of cylindrical or coated cylindrical inclusions. In an attempt to consider the influence of nonlinear order to effective nonlinear response, we assume that every constituent of the composites obeys a current-field relation of the form J =Χ|E|^βE. In dilute limit, we have presented some numerical results for the case of the third-order nonlinearity (i.e.β= 2) and the fifth-order nonlinearity (i.e.β= 4), and compared the effective response of the third-order nonlinearity with that of the fifth-order nonlinearity, some conclusions are drawn.
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  Resonant Tunneling Through a Quantum Dot in the presence of Alternating Fields

  Li-Jun LIU, Tsung-Han LIN

  理论物理通讯. 1997, 27(4): 407-412.

  摘要 ( 393 ) PDF全文 ( 784 )   可视化   收藏

  We have derived an analytical expression of the transmission probability through a quantum dot under an alternating field by using the nonequilibrium Green function techniques. The calculation. results show a simultaneously quenching in all side bands which are reported by Wagner recently. In addition, the theory of Jauho et al. has been applied to accounting for the latest experiments by Kouwenhoven et al. The mechanism leading to the zero bias current and its sign change is attributed to the photon-assisted-tunneling process.
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  Localization of Plasmons in Finite Three-Tile Quasiperiodic superlattices

  Nian-Hua LIU, Wei-Guo FENG, Xiang WU

  理论物理通讯. 1997, 27(4): 413-418.

  摘要 ( 386 ) PDF全文 ( 702 )   可视化   收藏

  The plasmons in a finite array of coupled two-dimensional electron gases arranged in a threetile quasiperiodic sequence are studied. We calculate the dispersion relation and investigate the localization of the plasmons. For a given in-plane wavevector the discrete modes form a series of bands. Extended and localized modes may coexist in the three-tile quasiperiodic superlattices. The plasmons in low frequency bands are localized. Extended modes appear in the middle bands. Some Tamm-like surface modes are found.
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  First-Order mansition in a Quantum Ising Model with p-Spin Interactions and a Random Field

  Yu-Qiang MA, Z. D. WANG, Li SHENG, Jian-Xin ZHU, Chang-De GONG

  理论物理通讯. 1997, 27(4): 419-422.

  摘要 ( 392 ) PDF全文 ( 727 )   可视化   收藏

  We study a quantum transverse Ising model with pspin interactions in the presence of a random field. The formulation for the free energy of the system is derived by making use of the Suzuki-Trotter approach with the thermodynamic perturbation theory, and the first-order transitions are obtained in the limit p→∞.
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  Numerical Study of the Kneading Theory for the Lorenz Model

  Wei-Mou ZHENG, Jun-Xian LIU

  理论物理通讯. 1997, 27(4): 423-428.

  摘要 ( 432 ) PDF全文 ( 739 )   可视化   收藏

  To a good approximation, the Lorenz attractor in the Poincark section may be viewed as a one-dimensional object. A family of maps proposed by Sparrow models the Lorenz system very well. Such maps are numerically constructed. Under the guide of the kneading theory for the maps a numerical study of the Lorenz system is conducted.
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  Baxter-Bazhanox Model, Frenkel-Moore Equation and the Braid Group

  Zhan-Ning HU

  理论物理通讯. 1997, 27(4): 429-434.

  摘要 ( 374 ) PDF全文 ( 716 )   可视化   收藏

  In this paper the three-dimensional vertex model is given, which is the duality of the threedimensional Baxter-Bazhanov (BE) model. The braid group corresponding to Frenkel-Moore equation is constructed and the transformations R, I are found. These maps act on the group and denote the rotations of the braids through the angles π about some special axes. The weight function of another three-dimensional .vertex model related the 3D laettice integrable model proposed by Boos, Mangazeev, Sergeev and Stroganov is presented also, which can be interpreted as the deformation of the vertex model corresponding to the BB model.
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  Nonadiabatic Berry Phase of a Two-State System and Nonstationarity of Quantum States

  Y. A. LEI, J. Y. ZENG

  理论物理通讯. 1997, 27(4): 435-442.

  摘要 ( 405 ) PDF全文 ( 851 )   可视化   收藏

  The nonadiabatic Berry phases in the magnetic resonance under .various initial conditions are investigated and compared with ,the adiabatic Berry phase. The generaJ formalism for calculating the nonadiabatic Berry phase of a two-state system in terpls of the expansion of instantaneous energy eigenstates is presented. Some numerical calculations and discussions are made. The Berry phase of a two-statesystem under an impulsive interaction is addressed.
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  Eigenstates of the Operator a_qs^k and Their Antibunching Effect

  Ji-Suo WANG, Chang-Yong SUN

  理论物理通讯. 1997, 27(4): 443-448.

  摘要 ( 374 ) PDF全文 ( 433 )   可视化   收藏

  In this paper, the mathematical structure and properties of k orthonormalized eigenstates of the higher powers a_qs^k(k≥3) of the annihilation operator of two-parameter deformed harmonic oscillator are studied. Based on the work, the antibunching properties of them are investigated. It is found that they may form a complete Hilbert space, and all of them show antibunching effect.
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  A Possible Signal of Six-Quark Clusters in Deuteron Electrodisintegration

  Tan-Sheng CHENG, Yu-Shu ZHONG, Lan-Chun LU

  理论物理通讯. 1997, 27(4): 449-456.

  摘要 ( 347 ) PDF全文 ( 482 )   可视化   收藏

  Deuteron electrodisintegration cross section in threshold region has been calculated by using the Kisslinger's hybrid quark-hadron model, including isoscalar MEC. The appearance of the second mgximum can be explained by the dependence of cross section on E_np, and may be the signal of six-quark clusters.
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  Extraction of α From the CP Asymmetry in B⁰/B⁰→π⁺π^- Decays

  G. Kramer, W. F. Palmer, Y. L. WU

  理论物理通讯. 1997, 27(4): 457-464.

  摘要 ( 415 ) PDF全文 ( 543 )   可视化   收藏

  The influence of strong and electroweak penguin amplitudes in B/B→π⁺π^- is investigated in connection with the determination of the unitarity triangle angle a of the CKM matrix. A relation between the observable asymmetry, the angle α, and the penguin amplitude is established. A model calculation of the penguin amplitude shows that the CP asymmetry in B⁰→π⁺π^- decays is only mildly influenced by the penguin amplitudes. Experimental limits on pure penguin and penguin dominated processes are consistent with the model. This information also suggests in a rather model-independent way that penguin amplitudes will not be a serious complicating factor in the determination ofa from the π⁺π^- time-dependent asymmetry.
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  Dependence of Jet Photoproduction on Scales in Higher Order QCD Corrections at HERA

  Yun-De LI, Lian-Shou LIU

  理论物理通讯. 1997, 27(4): 465-468.

  摘要 ( 412 ) PDF全文 ( 598 )   可视化   收藏

  The dependencies of two-jet cross section on renormalization scale and factorization scales of resolved photon and proton are investigated up to next-to-leading order (NLO) QCD. It is shown that the NLO cross section is quite sensitive to the choice of the renormalization scale and the factorization scales of resolved photon and proton in large invariant mass and large negative. rapidity of the two-jet system.
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  q-Deformed SU_q(2), Quark Mixing and the Cabibbo-Kabayashi-Maskawa Matrix

  Yong LIU, Xue-Qian LI, Li LIAO, Jing-Fa LU

  理论物理通讯. 1997, 27(4): 469-474.

  摘要 ( 368 ) PDF全文 ( 797 )   可视化   收藏

  In this work, we assume that the mass matrix of d-type quarks can be expressed in terms of SU(2) generators in the adjoint representation and the1 mass matrix of u-type quarks is related to M_d by a q-deformation. With only six parameters including the q-value, we obtain the six quark masses and the three Cabibbo-Kabayashi-Maskawa angles which are consistent with the present experimental values.
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  Infinite Degenerate States and Hawking Flux Quantization of Two-Dimensional Black Hole

  Yi-Xin CHEN

  理论物理通讯. 1997, 27(4): 475-480.

  摘要 ( 351 ) PDF全文 ( 530 )   可视化   收藏

  We further investigate the exactly solvable quantum corrected two-dimensional dilatongravity theories. For a fixed choice of boundary conditions, there exist the infinite symmetries on the equations of motion and the constraint equations in such a theory. The generators of these symmetries obey the relations of W_∞ algebra. They can be used to generate infinite degenerate states of two-dimensional black hole. The existence of the infinite static and non-static solutions results in quantization of the Hawking flux in the procedure of black hole evaporation.
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  General Deformation Scheme of Heisenberg-Weyl Algebra

  He-Shan SONG, Mill ZHANG, Ying AN

  理论物理通讯. 1997, 27(4): 481-484.

  摘要 ( 380 ) PDF全文 ( 629 )   可视化   收藏

  General deformation schemes for both bosonic and fermionic algebras of harmonic oscillator are studied in terms of explicit matrix representations of basic operators and a restriction relation for deformation function is discussed.
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  Excited States of the Double sine-Gordon Model

  Wen-Fa LU, Bo-Wei XU, YU-Mei ZHANG

  理论物理通讯. 1997, 27(4): 485-488.

  摘要 ( 304 ) PDF全文 ( 610 )   可视化   收藏

  Using the Gaussian wave functional as variational ground state, we study the excited states of the double sine-Gordon model in (D+1) dimensions. We find, i) for D < 3 there exist twoparticle bound states, their energy decreases with increasing coupling; ii) also for D < 3, the phase shift of the two-particle scattering state is always positive; iii) for D ≥ 3 the investigation on the interaction between the particles shows that the theory is trivial.
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  Chaotically Temporal Retrieval of Memory

  Chang-Song ZHOU, Tian-Lun CHEN

  理论物理通讯. 1997, 27(4): 489-496.

  摘要 ( 423 ) PDF全文 ( 811 )   可视化   收藏

  A neural network with nonlinear delays to produce temporal retrieval of memory is presented. In this network, chaotic motion of the local fields provides a mechanism for the system to escape from one memory to another. It is proved by numerical investigations that the chaotic temporal process can explore the topological structure of the state space and the system has better efficiency of searching global minimum of the energy function than the Hopfield model. The characters of the system show that it may have great potential use in solving combinatorial optimization problems with its complex dynamics.
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  Gravity with Electromagnetism on M⁴ × Z₂

  Bin CHEN

  理论物理通讯. 1997, 27(4): 497-500.

  摘要 ( 364 ) PDF全文 ( 565 )   可视化   收藏

  In the framework of the differential calculus on discrete group, which is a realization of noncommu tative geometry, we present a Kaluza-Klein-type unified Einstein-Maxwell theory on M⁴ × Z₂. By generalizing the usual concept ofi vielbein and connection and from the generalized torsion-free condition, we obtain a gravity theory which contains tensors, vectors and scafar field.
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  Operator Gauge Potential and the canonical Quantization Condition

  Ning WU, Tu-Nan RUAN

  理论物理通讯. 1997, 27(4): 501-502.

  摘要 ( 350 ) PDF全文 ( 607 )   可视化   收藏

  We discuss that a special kind of self-in teraction forms a gauge potential, and the constraint of the gauge potential gives the canonical quantization condition.
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  Painlevé Property and Allowed Transformations of the Variable-Coefficient Zakharov-Kuznetsov Equation

  Chang-Zheng QU, Quan-Ju ZHANG

  理论物理通讯. 1997, 27(4): 503-506.

  摘要 ( 377 ) PDF全文 ( 559 )   可视化   收藏

  In this letter, we discuss the Painlevé property and allowed transformation for the variablecoefficient Zakharov-Kuznetsov equation which governs nonlinear ion-acoustic wqves in a magnetized plasma. The general solution of the singular manifold equation and stability solution of the VCZK equation are obtained. To prove some information of the integrability of the ZK equation, we prove the constraints that the variable-coefficient functions for the equation to possess the Painlevé property are not equivalent in order that the equations may be transformed into the constant coefficient equation. So we confirm that the ZK equation is not integrable.
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  Ω Production and Corresponding Ratio of Antiparticle to Particle in Relativistic Nucleus-Nucleus

  Ben-Hao SA

  理论物理通讯. 1997, 27(4): 507-510.

  摘要 ( 349 ) PDF全文 ( 589 )   可视化   收藏

  We use the event generator LUClAE to analyze the WA85 data of ratio of Ω^- to Ω^- in reaction (200A GeV/c)S + W. The result indicates that the reproduction of WA85 data might be achieved in hadronic rescattering regime of LUCIAE and might need not to rely on the formation of QGP.
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  The Universality of Dynamic Exponent θ' Demonstrated by the Dynamical Two-Dimensional Ising Model

  XiaeWei LIU, Zhi-Bing LI

  理论物理通讯. 1997, 27(4): 511-512.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  By means of Monte-Carlo simulation, we calculate the dynamic exponent θ', which governs the initial slip in the critical. relaxation, in triangular lattice with both heat-bath and Metropolis dynamical algorithms. Our best estimation for θ' is 0.1934(6) with the heat-bath algorithm and 0.195(2) with Metropolis algorithm. Comparing also to the results obtained in squeare lattices, we conclude that the universality hypothesis is consistent in our calculation.