2000年, 第33卷, 第2期　
刊出日期：2000-03-15

  

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  Calculation of Arbitrary Overlap Integrals over Slater Type Orbitals Using Basic Overlap Integrals

  I. I. Guseinov, B. A. Mamedov, M. Orbay, T. Özdogan

  理论物理通讯. 2000, 33(2): 161-166.

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  The recurrence relations are presented for the calculation of basic overlap integrals, by making use of which other overlap integrals are calculated analytically. These recurrence relations are especially useful for the calculation of any overlap integral for large quantum numbers. For the arbitrary values of screening constants of atomic orbitals and internuclear distances an accuracy of the computer results is satisfactory for the values of principal quantum numbers of Slater functions up to 50.
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  Energy Spectra and g Factors of α-A1₂0₃:Cr³⁺ and α-A1₂0₃:Mn⁴⁺

  MA DongPing, MA Ning, CHEN JuRong, LIN Qiang

  理论物理通讯. 2000, 33(2): 167-172.

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  By diagonalizing the complete d³ energy matrix in a trigonally distorted cubicfield and using the wavefunctions from it, unified calculations of the whole energy spectrum as well as the g factors of the ground state and t₂^{3 2} E excited states for α-A1₂0₃:Cr³⁺ and α-A1₂0₃:Mn⁴⁺ have been carried out respectively. A11 the calculated results are in very good agreement with the experimental data. The comparison between the results of the two crystals has been made, which demonstrates that the covalency of α-A1₂0₃:Mn⁴⁺ is stronger than the one of α-A1₂0₃:Cr³⁺. For the zero-field splittings of the ground state and t₂^{3 2} E , their physical origins are revealed; the comparison and analysis of their values of the two crystals have been made.
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  Chiral Quark Model with Topological Ghost

  YANG Shu, LÜ XiaoFu, ZHAO EnGuang

  理论物理通讯. 2000, 33(2): 173-176.

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  A nonlinear chiral quark model with topological ghost terms is proposed. The couplings among the light-flavor quarks, the Goldstone boson nonet and the topological ghost field are consistently incorporated in the model. The inclusion of the ghost field coupling is demanded by describing correctly the effect of the axial U(1) anomaly Some features of the model are discussed.
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  The Universal Electronic Thermal Conductivity in the d-Wave Superconductor with Nonmagnetic Impurities

  QI XiaoYa, XU wang, LI ZhengZhong

  理论物理通讯. 2000, 33(2): 177-184.

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  The low-temperature electronic thermal conductivity of the d-wave superconductors with nonmagnetic impurities is calculated within the framework of coherent potential approx-imation. The result shows that at low concentration, the low-temperature linear term of the thermal conductivity κ in the superconducting state is almost independent on the scattering rate or the concentration of the impurities. However, as the concentration increases, the universal value κ/T increases monotonously with the impurity concentration. A possible form of order parameter that may reduce the discrepancy between the theoretical value of κ/T and the measured value is also suggested.
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  Resonant Photon-Assisted Tunneling Through a Coupled Double-Quantum-Dot System

  DU ShangFeng, SUN QingFeng, LIN TsungHan

  理论物理通讯. 2000, 33(2): 185-190.

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  An analytical formula of the tunneling current through a coupled double-quantumdot system in the presence of a time-dependent electric field is obtained by using the Keldysh nonequilibrium Green's function technique. The dependence of the time-averaged current on the frequency of the electric field, as well as the dependence of the multiphoton assisted tunneling on the strength of the electric field are studied. The features of I-V_dc characteristic are also investigated. Besides, we present a simplified formula which can be used to determine the heights of the resonant peaks conveniently.
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  Resonant Steps in the Discrete sine-Gordon Chain

  ZHENG ZhiGang, HU BamBi, HU Gang

  理论物理通讯. 2000, 33(2): 191-196.

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  Low-velocity dynamics of a dc-driven discrete sine-Gordon chain is studied in the damped case. It is shown that resonant steps of the average velocity emerge due to the resonant phase locking between the kink motion and its radiated linear modes in its wake. A mean-field description is given, which can predict precisely the numerical results. The mechanism and formula proposed in this paper can be directly applied to the discussion of fluxon dynamics of one-dimensional Josephson junction arrays and Josephson junction ladders.
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  Frequency-Dependent Stochastic Resonance in Globally Coupled Systems

  LIU Hong, HU Gang, ZHANG Ying, XIAO JinHua

  理论物理通讯. 2000, 33(2): 197-204.

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  A model of globally coupled bistable systems consisting of two kinds of sites, subject to a periodic driving and spatially uncorrelated stochastic force, is investigated. In the large system size limit, the problem of large number of coupled Langevin equations can be reduced to a simple problem of two coupled ordinary differential equations. Considering the finite size effect, we can derive two coupled Langevin equations. All the above three kinds of equations are numerically computed and compared with each other. Fkequency-dependent stochastic resonance is found, and the reduced equations can represent the high-dimensional system when the system size is large.
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  Monte Carlo Simulation of the Non-universal Short-Time Behavior for a Kinetic 2-D Ising Model

  YE AiJun, PAN ZhiGang, CHEN Yuan, LI ZhiBing

  理论物理通讯. 2000, 33(2): 205-208.

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  The short-time dynamic process for the two-dimensional Ising model with the nearest-neighbor coupling and the next-nearest-neighbor antiferromagnetic coupling in the critical domain is simulated by the Monte Carlo method. From the power law behavior of the initial order increase, the critical points and the initial dynamic exponent θ are determined.
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  Dynamical Properties of Bidirectional Ring Laser with Both the Additive and Multiplicative Noises and Saturation Effect

  LENG Feng, ZHU ShiQun

  理论物理通讯. 2000, 33(2): 209-216.

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  The dynamical properties of a two-mode ring laser with both the additive and multiplicative noises are analyzed. Time-dependent probability density is obtained by the method of one-dimensional approximation. Some special behaviors of T_c and λ_eff are discussed when the multiplicative pump noise and saturation effect are included in the laser theory.
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  Generalized Raynal-Revai Bracket for 1D Hyperspherical Harmonics

  XIE WenFang

  理论物理通讯. 2000, 33(2): 217-220.

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  We presented the transformation bracket of hypersphericid harmonics with different sets of hyperspherical coordinates as arguments for an arbitrary number of particles with arbitrary masses in one-dimensional space.
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  The Branching Rules for U(7)⊃0(7)⊃G₂⊃0(3)

  RUAN Dong, SUN HongZhou

  理论物理通讯. 2000, 33(2): 221-226.

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  The branching rules for U(7)⊃0(7)⊃G₂ and G₂⊃0(3) for at most fourcolumned IRs of U(7)) and O(7) are given respectively by using the method of decomposition of Kronecker products of IRs of groups. The needed formulae for decomposition of Kronecker products of IRs of O(7) and G₂ are given also.
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  Independent Descriptions of the collective Degrees of Freedom of Nuclei (I)

  LU DaHai, YANG LiMing

  理论物理通讯. 2000, 33(2): 227-231.

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  The present paper at tempts to give independent descriptions of the collective degrees of freedom of nuclei such as the monopole and quadrupole ones in order to avoid the seniority mixing problem. This is done by the operatorized Bogoliubov transformation (OBT) which separates the s degree of freedom from the rest described by the seniority particle operator which is not coupling to the S pairs, and in terms of which the independent D pair is composed. The OBT is derived in such a way that it can be generalized easily to include a new kind of 'keniority particle operatorJ' neither coupling to the S nor to the D pairs. In terms of this new particle operator the independent G pair or the independent odd particle in odd A nuclei is constructed.
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  Independent Descriptions of the Collective Degrees of Freedom of Nuclei (II)

  LU DaHai, YANG LiMing

  理论物理通讯. 2000, 33(2): 232-240.

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  The operatorized Bogoliubov transformation introduced in the previous paper is generalized so that it can be used in microscopic descriptions of the collective degrees of freedom independent of both the monopole and quadrupole degrees of freedom.
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  The Invariant-Relat ed Unitary Transformation Method and the Evolution of a Dirac Field in Friedmann-Robertson-Walker Flat Spacetimes

  FU Jian, GAO XiaoChun, XU JinBo, ZOU XuBo

  理论物理通讯. 2000, 33(2): 241-252.

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  On the basis of the generalized invariant formulation, the invariant-related unitary transformation method is used to study the evolution of a quantum Dirac field in Friedmann-Robertson-Walker spatially flat spacetime. We first solve the functional Schrodinger equation for a free Dirac field and obtain the exact solutions. We then investigate the way of extending the method to treat the case in which there is an interaction between the Dirac field and a scalar field.
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  Effective Two-Loop Thermodynamic Potential with Fermions in the Real-Time Formalism of Thermal Field Theory

  WANG Xin, LI JiaRong

  理论物理通讯. 2000, 33(2): 253-262.

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  Within the real-time formalism of thermal field theory, we apply the hard thermal loop resummation technique to calculate effective two-loop thermodynamic potential in quarkgluon and its renormalization. The result with collective effects is obtained, which is valid for an arbitrary number of quark flavors with masses.
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  Space-Like Form of Bethe-Salpeter Equation: Bound State

  WANG AnMin, RUAN TuNan

  理论物理通讯. 2000, 33(2): 263-268.

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  According to Dirac's principle, we apply the space-like consistency conditions in a relativistic theory to two-particle system and then define the space-Like wavefunctions through introducing a space-like factor, which is equivalent to Bethe-Salpeter wavefunction in physical content. The space-like form of Bethe-Salpeter equation of bound states is derived in terms of the universal rearranging technology of interaction kernel. Its advantages are of explicit Lorentz-covariant form and the difficulty of ghost states is automatically overcome. We also discuss the normalization condition of the space-like function.
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  Rare Decays B → X_S,dνν and X_S,d → l⁺l^- in the ,Topcolor-Assisted Technicolor Model

  XIAO ZhenJun, JIA LiQun, LU LinXia, LÜ GongRu

  理论物理通讯. 2000, 33(2): 269-274.

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  We calculate the contributions to the rare decays B → X_S,dνν and X_S,d → l⁺l^- from one-loop Z^o -penguin diagrams in the framework of topcolor-assisted technicolor model. Within the parameter space, we find that: (a) the new contribution from technipions is less than 2% of the standard model prediction; (b) the top-pions can provide a factor of 10 to 30 enhancement to the ratios in question; (c) the topcolor-assisted technicolor model is consistent with the current experimental'data.
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  Leading Electroweak Corrections to the Neutral Higgs Boson Production at the Fermilab Tevatron

  CAO QingHong, LI ChongSheng, ZHU Shou Hua

  理论物理通讯. 2000, 33(2): 275-284.

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  We calculate the leading electroweak corrections to the light neutral Higgs boson production via qq → WH at the Fermilab Tevatron in both the standard model and the minimal supersymmetric model, which arise from the top-quark and Higgs boson loop diagrams. We found that the leading electroweak corrections can exceed the QCD corrections for favorable values of the parameters in the MSSM, but such corrections are only about -2%~-4% in the SM, which are much smaller than the QCD corrections. For the mass region of 90 < mh, < 120 GeV, the leading electroweak corrections can reach -20% for large tan β, and these corrections may be observable at a high luminosity Tevatron; at the least, new constraints on the tan β can be established.
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  The ρ-π Puzzle of J/φ and φ′ Decays

  TUAN SanFu

  理论物理通讯. 2000, 33(2): 285-290.

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  The recent BES Collaboration data on φ →PV, particularly the isospin violating mode φ′ → π^oω^o and finding of a finite number for B(φ′ → K^*OK^O), enable us now to deal more precisely about the challenges to theory concerning this extraordinary and remarkableso-called ρ-π puzzle of J/φ and φ′ decays. In terms of the existing data and deploying the simplest phenomenology, measurement of φ′ → π⁺π^- and whether a finite number for the K^*+K^- mode might require a significantly large accumulation of data remain interesting questions.
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  Pion Properties as a Goldstone Boson in the Dual Ginzburg-Landau Theory

  YAN ZhiTao, GAO ChongShou

  理论物理通讯. 2000, 33(2): 291-296.

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  By solving the Schwinger-Dyson equation for quark self-energy and Bethe-Salpeter equation for pseudo-scale vertex, we investigate the static pion properties in the dual Ginzburg-Landau Theory that includes a description of confinement. Pion mass formula and the Gell-Mann-Oakes-Rennner relation are shown. The pion mass, resulting from the current quark mass, and pion decay constant are calculated. Our results show that the dynamical effect of light quarks is unimportant for the mass of pion.
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  Variational Cumulant Expansion Study of Z(N) Lattice Gauge Theory with Symanzik's Improved Action

  LU Qiang, CHEN TianLun, LI Hong

  理论物理通讯. 2000, 33(2): 297-300.

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  With the variational cumulant expansion (VCE) method, the internal energy and the specific heat of the Z(N) lattice gauge theory with Symanzik's improved action are calculated up to the third order. The variational parameter is determined by the main valued method and the result is compared with the VCE result for standard Wilson action. Furthermore, the changes are compared with those of the SU(2) case.
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  Stability of an Isothermal Disk with Three-Dimensional Magnetic Fields and Radial Viscous Force

  DING Shixue, YANG LanTian, WANG DaZhi, LU Ye

  理论物理通讯. 2000, 33(2): 301-308.

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  The stability of an isothermal thin disk with three-dimensional magnetic fields and radial viscous force is examined in this paper. We find that the radial viscous force has no influence on the stability of viscous modes. But there is more influence on the stability of magneto-acoustic modes, which is related to the perturbation wavelength and different parts of disk. Finally, we use our model to explain the long-term variability of Quasar 3C345.
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  Quantum Superposition of Two Coherent States in a Mesoscopic Josephson Junction

  ZOU Jian, SHAO Bin

  理论物理通讯. 2000, 33(2): 309-312.

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  We study a mesoscopic Josephson junction in a circular superconducting ring which encloses a magneto static flux. It is shown that with the junction being initially prepared in vacuum state, the state of the junction can evolve into a quantum superposition of two coherent states.
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  Entangled States and the Wigner Operator of the Complex Scalar Fields

  FAN HongYi, FAN Yue

  理论物理通讯. 2000, 33(2): 313-316.

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  By introducing the Wigner operator into the complex scalar field we show that the newly constructed common eigenvector of scalar field φ(x) and φ⁺(x) is an entangled state. The properties of field Wigner operator is also discussed.
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  Nucleon Tensor Charge from the Quark Model

  HE HanXin

  理论物理通讯. 2000, 33(2): 317-320.

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  The ndcleon tensor charge is studied in the quark model. It is found that the contributions from valence constituent quarks are δu_q = 1.17 and δu_g = -0.29, while the contributions from valence current quarks are δu_v = 0.89 and δu_v = -0.22 at scale about 1 Ge V.