1990年, 第13卷, 第4期　
刊出日期：1990-06-15

  

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  Damping Effects on the Reflection of the Metallic Superlattice for Soft X-Rays and Extreme Ultraviolet

  He-sheng YA0, Wei-guo FENG, Xiang WU

  理论物理通讯. 1990, 13(4): 425-432.

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  Based on the hydrodynamic model theory and the transfer-matrix-method, we have reexamined the reflection properties by taking account of damping effects to the system of the metallic superlattice for the S-polarized soft X-rays and extreme ultraviolet. Fot the normal incidence, we find that the reflection intensity spectxm will decline monotonously with the increasing of the retardation, but for the regions of the higher frequencies and the smaller grazing angles, the damping effects could be neglected.
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  Magnetic Phase Transitions in Quantum Ising Model with Annealed Antiferromagnetic Bond Randomness

  Zhu-pei SHI, Rui-bao TAO

  理论物理通讯. 1990, 13(4): 433-440.

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  The effect of annealed antiferromagnetic bond randomness on the phase transitions of the Quantum Ising Model (QIM) is studied by using mean-field renormalization group method. It is argued that bond randomness drastically alters multicritical phase diagram via transverse field. Multicritical points and coexistence region of ferromagnetic and antiferromagnetic case exist only at weak transverse field,.and are entirely eliminated at strong transverse field. The coexistence region diminishes in reducing the fluctuation interaction. This physical picture demonstrates that the competition between transverse field and exchange interaction and fluctuation interaction via bond randomness play an important role in generating multiphase structure. Another consequence of competition is that tricritical points of first-second order phase transitions are not entirely eliminated by bond randomness in two-dimensional QIM.
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  Closed Time-Path Green Functions by Stochastic Quantization

  CHEN Ren

  理论物理通讯. 1990, 13(4): 441-448.

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  The Langevin equation and the Gaussian average of the stochastic quantization of Parisi and Wu are continued on the closed time-path, at the same time, the new non-Gaussian soirce is added into it. After assuming some properties of new source, the closed time-path Green functions are computed by using the adapted Langevin equations. While they are transformed into the physical representation, some important characters of closed time-path Green function, i.e. the normalization and causality, are obtained also.
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  Pion Induced Double Charge Exchange Reaction at Pure Nucleonic Level

  CHING Cheng-rui, HO Tso-hsiu, ZOU Bing-song

  理论物理通讯. 1990, 13(4): 449-456.

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  The two pure nucleonic mechanisms (the conventional sequential mechanism and the two-nucleon pion absorption-emission mechanisml^[1]) are studied within a unified framework of Distorted Wave Impulse Approximation (DWIA). The distorted pion waves are obtained by solving the Klein-Gordon equation with the first-order optical potential. The difference between this approach and the eikonal approximation is showed. For the two-nucleon pion absorption-emission mechanism the effective Landau-Migadal interaction of Pines, et al.^[2] is used for the two bound nucleons, the result is compared with that by using the Paris force. By combining theee two mechanism the O⁰ excitation functions for the DCX reactions to the isobaric analog states on the ¹⁴C, ¹⁸O, ²⁶Mg and ⁴²Ca are calculated and compared with the experimental data.
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  Skyrme Forces and Their Applications in Low Energy Nuclear Physics

  LI Guo-qiang

  理论物理通讯. 1990, 13(4): 457-508.

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  This paper reviews the present status of Skyrme forces and their applications in the field of low energy nuclear physics as an effective nucleon-nucleon interaction. Their applications in the following five domains are presented:1). Hartree-Fock (HF), selfconsistent semiclassical (SCSC) calculations and nuclear ground state properties;2). random phase approximation (RPA), sum rule approach and properties of nuclear giant resonances;3). calculations of microscopic nucleon-nucleus optical potentials and related quantities;4). calculations of nucleus-nucleus optical potentials and fusion barriers;5). multifragmentation, liquid-gas phase transition and instability of hot/compressed nuclei.
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  Braiding and Fusion Matrices for Quantum Octet Representation

  MA Zhong-qi, YIN Yu-dong

  理论物理通讯. 1990, 13(4): 509-516.

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  The braiding and fusion matrices based on the octet representation of the quantum sl(3) enveloping algebra are computed. The multiplicity in the decomposition of the coproduct 8×8 manifests itself in those matrices.
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  Universally Treating the Quark Pair with a Vacuum Quantum Number in the Related Charm Decays

  Chao-hsi CHANG, Xue-qian LI, Jian-xiong WANG

  理论物理通讯. 1990, 13(4): 517-532.

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  A method for universally treating the quark pair with a vacuum quantum number is proposed and it is applied to calculating some charm meson decays zs examples. The smallness for W-exchange and annihilation mechanisms has new explanation and the result obtained by means of the proposed method on the D_s⁺→f0π⁺ de cay fits the experimental data well.
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  Gravitational Correction to Hyperfine Structure

  Shu-xue DING, He-shan SONG, Ying AN

  理论物理通讯. 1990, 13(4): 533-542.

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  The effective Hamiltonian of a fermion with spin-spin coupling to another fermion is derived from the non-relativistic approximation of the generally covariant Dirac equation in a weak gravitational field. This makes hyperfine structure of s-state of atomic hydrogen to be triplet other than the doublet in fiat spacetime. The difference is large enough to be measured for the atomic hydrogen on the earth and the sun.
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  Relativistic Cloud-In-Cell Simulation of Free Electron Laser

  ZHANG Jia-tai, LU Zheng-qiang, CHANG Tie-qiang, WANG Shi-hong, XU Lin-bao, ZHANG Shu-gui, TAO Yin-xue, LIU Xiu-qin

  理论物理通讯. 1990, 13(4): 543-548.

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  We have developed one-and a half-dimensional (one space dimension and two velocity components) relativistic electromagnetic cloud-in-cell simulation (CIC-R) code which is suitable for simulating the free-electron laser process. Using CIC-R we have simulated the temporal evolution of the free-electron laser, and obtained the results on the linear growth rates of the unstable spectrum and the dispersion relation of the coupling between the electromagnetic waves and electrostatic waves which agree with the theory. Other results such as the time development of the electron distribution function, nonlinear saturation and the efficiency of energy conversion are also presented in detail.
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  Remarks on the Possibility of Cold Fusion

  WANG Rong

  理论物理通讯. 1990, 13(4): 549-556.

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  Various hypotheses of cold fusion are enumerated and examined. Except muoncatalyzed fusion, no real possibility of cold fusion haa been found.
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  The Shallow Donor Impurity State Near a Polar Crystal Surface

  SHEN Zhong-jun, YUAN Xiao-zhong, GU Shi-wei

  理论物理通讯. 1990, 13(4): 557-562.

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  We report the results of a variational calculntion for the ground state of a near surface hydrogenic donor interacting with both surface and bulk longitudinal optical (SO and BO) phonons in polar crystals. In calculation we also consider the effect of the image potentials. The variations of ground state energies and binding energies with R are given for some materials.
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  Causality and Transition Amplitude in Relativistic Quantum Mechanics

  Bang-rong ZHOU

  理论物理通讯. 1990, 13(4): 563-568.

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  The constraint from causality on transition amplitude in relativistic quantum mechanics (x, γ|0, o)=0 when γ²-|x|²<0 is proven for Dirac particle without and with interactions with external fields and for free scalar and vector particle in any (1+D)-dimensional Minkowskian space-time.