2000年, 第34卷, 第4期　
刊出日期：2000-12-15

  

• 全选
  |

• Select
  An Extended Landauer Conductance Formula in High-Dimensional Case

  AN Jin, GONG ChangDe

  理论物理通讯. 2000, 34(4): 577-582.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  A Landauer-like formula of high-dimensional conductance is obtained. As before, conductance u is expressed by the averaged transmission and reflection coefficients, but with correction from dimensionality and material properties. As an application, we have obtained the length dependence of conductivity under two different conditions.
• Select
  Spin-Polarized Electron Tunneling Through a Quantum Dot

  LU Yu, SUN QingFeng, LIN TsungHan

  理论物理通讯. 2000, 34(4): 583-592.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Nonequilibrium Green's function is uscd to study spin-polarized electron tunneling through a quantum dot connected to two ferromagnetic electrodes with different orientations via two insulating barriers (FM/I/QD/I/FA.f). Intra-level Coulomb interaction in the dot is considered. General formula of tunneling current which can be used for arbitrary angle between the two electrodes' magnetizations is derived for both the weak and strong intra-dot interactions.We find that the transport current can be divided into two parts: the current with the spin-flip and the current without the spin-flip, which critically depend on the linewidth function near the Fermi level of the ferromagnetic electrodes. If a magnetic field is applied in the quantum dot, different behaviors will be found for weak and strong interactions.
• Select
  Mechanism for the Correlated Swinging of Photoluminescence Intensity and Peak Energy Shift with Sizes of Nanoscale Si Particles

  WANG SiHui, LIAO LiKai, QIN GuoYi, QIN GuoGang

  理论物理通讯. 2000, 34(4): 593-604.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Based on the quantum confinement-luminescence center model, we focus on the relationship between the photoluminescence (PL) spectra and sizes of nanoscale silicon particles.We find that when there are two kinds of luminescence centers (LC) in the oxide layer surrounding the silicon particles, both the integrated PL intensity and the spectral peak position swing with reducing the sizes of silicon particles, which is different from the monotonous blueshift of peak position predicted by quantum confinement model. By changing the concentrations of LC we find the correlation between the spectral peak position and the integrated PL intensity when the size of silicon particles is reduced. The effects of other parameters such as the half width of size distribution and the position of photon emission levels of LC are also found to be important.
• Select
  g Factors and Energy Spectrum of MgO:V²⁺ and Their Pressure-Induced Shifts

  MA DongPing, MA Ning, LIN Qiang, CHEN JuRong

  理论物理通讯. 2000, 34(4): 605-616.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The calculations of the whole energy spectrum and the g factors of the ground state and t₂^{3 2}E excited state for MgO:V²⁺ at normal pressure as well as their pressure-induced shifts have been carried out on the basis of the theory of pressure-induced shifts and the diagonalization of the complete d³ energy matrix in a regular octahedral field. The calculated results are in very good agreement with experimental data. It is found that in the range of 1 bar ～ 100 kbar, the g value of the ground state increases monotonously with pressure, but the g value of t₂^{3 2}E excited state for MgO:V²⁺ decreases at first, and then increases. For the first time, the physical essentials of the pressure-induced shifts of g values for the ground state and t₂^{3 2}E excited state have been thoroughly analyzed and revealed by taking into account the wavefunctions, energy spectra and orbital-angular-momentum reduction factors at various pressures.
• Select
  Unitary Evolution and Quantum Fluctuation in SQUID

  SHAO Bin, ZOU Jian, LI QianShu

  理论物理通讯. 2000, 34(4): 617-622.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  bstractA circular superconductor with a weak-link junction is considered in the presence of a dc voltage bias. Using a time-dependent perturbed method, we obtain a unitary evolution operator of the driven SQUID system. We investigate the step structure of the screening current in the system and show that, due to the Josephson nonlinear term, the Aux and charge can exhibit reduced quantum fluctuation behavior.
• Select
  Spin-Wave Excitations in Anisotropic Kondo Lattice Model

  WANG XiaoBing, GU BingLin

  理论物理通讯. 2000, 34(4): 623-630.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The spin-wave excitations in anisotropic Kondo lattice model are studied using the spin Green's function. Both the ferromagnetic and antiferromagnetic cases are considered. The equations to determine the spectrum of low-energy excitations are given. The anisotropy gaps are obtained, and the long-wavelength and strong-coupling limits are analyzed.
• Select
  Phase Transition in Two-Dimensional Josephson-Junction Arrays

  LIU JinMing, GUO ShuoHong, LI JieMing, FANG XiYan, SET0 SuePing

  理论物理通讯. 2000, 34(4): 630-634.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The self-charging model of two-dimensional Josephson-junction arrays at T = 0 is studied by the coupled cluster expansion method. The calculated results for the mass gap converge nicely. Besides the critical point, we also determine the critical parameters at T = 0. The system displays a second-order phase transition and the results are consistent with those obtained by other methods.
• Select
  The Lax Pair and Boundary K-Matrices for XXC Model

  LI GuangLiang, HOU BoYu, SHI KangJie, YUE RuiHong, FAN Heng

  理论物理通讯. 2000, 34(4): 635-642.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The Lax pair and corresponding boundary K-matrices for the XXC model are derived. The time-independent transfer matrix with the spectral parameter is constructed, which means the system to be Lax integrable. Our K-matrices include the result used by Arnaudon and Martssarani (D. Arnaudon and Z. Maassarani, lapth-695/98, laval-phy-22/98) as a special case.
• Select
  Indecomposable Represent at ions of the Nonlinear Angular Momentum Algebra of Quadratic Type

  RUAN Dong, WANG Fang, TU ChangCun, SUN HongZhou

  理论物理通讯. 2000, 34(4): 643-648.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The explicit expression for indecomposable representation of the nonlinear angular momentum algebra of quadratic type, J₂, on the space of its universal enveloping algebra is given. Then, from this indecomposable representation, other indecomposable (irreducible) representations are derived which are induced on quotient spaces or subduced on invariant subspaces. The inhomogeneous boson and differential realizations of J₂ are obtained from the Fock representations corresponding to the indecomposable represen'tations.
• Select
  Deforming the Lower-Dimensional Solitons to Higher-Dimensional Ones

  LOU SenYue

  理论物理通讯. 2000, 34(4): 649-654.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  For high-dimensional models, to find some types of soliton (or solitary wave) so-lutions localized in all .directions is a very difficult work. In this letter, we propose a simple idea to deform a soliton solution of a lower-dimensional integrable model to that of a higherdimensional model. The deformation procedure may be considered as an inverse procedure of the well-known symmetry reduction approach. Some new exact solitons of a (2+1)-dimensional sine-Gordon equation are discussed.
• Select
  Hadron Mass and the Properties of Nuclear Matter in the Quark Bag Models

  LIU LiangGang

  理论物理通讯. 2000, 34(4): 655-662.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The MIT bag model, chiral bag model and cloudy bag model are revisited. A typical work on the hadron mass calculation by chiral bag model and cloudy bag model is shown in more details with the quark-quark-pi vertex correction and quark self-energy being emphasized. More details are given to review the quark-meson coupling model and its application in nuclear matter. We put forth the Lagrangian of the quark-meson coupling model and studied the possibility of using the model to calculate the hadron mass.
• Select
  A Phenomenological Expression for Deuteron Electromagnetic Form Factors Based on Perturbative QCD Predict ions

  WU HuiFang, CAO Jun, HUANG Tao

  理论物理通讯. 2000, 34(4): 663-668.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  For deuteron's electromagnetic form factors, perturbative QCD (pQCD) predicts that G₀₀⁺ becomes the dominate helicity amplitude and G₊₀⁺ and G_{+ -}⁺ are suppressed by factors A_QCD/Q and A_QCD²/Q² at large Q² respectively. We try to discuss the higher-order corrections beyond the pQCD asymptotic predictions by interpolating an analytical form to the intermediate energy region. From fitting the data, our results show that the helicity-zero to zero matrix element G₀₀⁺ dominates the gross structure function A(Q²) in both the large and intermediate energy regions. It is a good approximation for G_{+ -}⁺ to ignore the higher-order contributions and the higher-order corrections to G₊₀⁺ should be taken into account due to sizeable contributions in the intermediate energy region.
• Select
  Chargino-Pair Productions via Drell-Yan Process at the LHC

  ZHOU Hong, MA WenGan, HAN Liang, JIANG Yi, ZHOU MianLai

  理论物理通讯. 2000, 34(4): 669-676.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  We present the analytical and numerical investigations of chargino-pair productions via Drell-Yan process a t proton-proton collider in the frame of minimal supersymmetric extension at tree level. For the χ_i⁺χ_j^-(i,j= 1,2) pair productions at the LHC, the cross section is in the order of 3～2.5 ×10^-3 pb. We find that the cross sections of all kinds of chargino-pair production processes are strongly related to the SUSY Lagrangian parameters M₂ and μ.
• Select
  Glueballs and Instantons in Lattice SU(2) Gauge Theory

  CHEN Ying, HE Bing, LIN He, WU JiMin

  理论物理通讯. 2000, 34(4): 677-682.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The SU(2) glueball masses and the gluonic correlation functions in the J^P = 0⁺,2⁺ and 0^- channels are calculated from the cooled and uncooled gauge configurations. The improved action and the anisotropic lattice are used in this work. The instanton-induced attractive force in the 0⁺ channel and the repulsive force in the 0^- channel are confirmed by the Monte Carlo simulation. There is evidence that the instanton vacuum contribution to the 0⁺ glueball mass is significant.
• Select
  Derivation of Effective Chiral Lagrangian for the Whole Nonet Pseudo-Scalar Goldstone Bosons from QCD

  WANG XueLei, WANG ZhiMin, WANG Qing

  理论物理通讯. 2000, 34(4): 683-704.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The effective chiral Lagrangian derived from underlying QCD for pseudo-scalar Goldstone bosons has been generalized to involve the whole nonet pseudo-Goldstone bosonk, no approximation is made in the derivation. The formulation offers general QCD definitions for the coefficients in effective chiral Lagrangian.
• Select
  Triality and Quantization of Singularities in Massive Fermion

  LIU YuFen

  理论物理通讯. 2000, 34(4): 705-714.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  It is proved that fermions can acquire the mass through the additional non-integrable exponential factor. For this propose the special vector potential associated with the spinor field was introduced. Such a vector potential has closk relation with the. triality property in Dirac spinors and plays crucial role in the construction of massive term. It is shown that the change in phase of a wavefunction round any closed curve with the possibility of there being singularities in our vector potential will lead to the law of quantization of physical constants including the mass. The triality properties of Dirac's spinors are studied and it leads to a double covering vector representation of Dirac spinor field. It is proved that massive Dirac equation in the bosonic representation is self-dual.
• Select
  Generalized Two-State Theory for an Atom Laser and Its Interference

  YI XueXi, WANG HaiJun, SU JunChen, SUN ChangPu

  理论物理通讯. 2000, 34(4): 715-722.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  We present a generalized two-state theory to study the output coupler for Bose-Einstein condensate atoms and its interference. The results show that the fraction of outcoupled atoms can be adjusted between 0% and 100% by mrying the amplitude of the rf. radiation, and the interference patterns of the two coherent outputs that are coupled out of a double-well trapped potential vary with time. Moreover, we study the influence of atom-atom interactions on the output. In contrast with the case without atom-atom interactions, collapses and revivals appear in the number of the output atoms.
• Select
  Hamilt onian Monte Carlo Application to (2+1)-Dimensional Quant um Mechanics

  JIANG JunQin, HUANG ChunQing, LUO XiangQian, Hamza Jirari, Helmut Kröger, Kevin Moriarty

  理论物理通讯. 2000, 34(4): 723-728.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Using a recently developed Hamiltonian Monte Carlo method, we compute the lowlying energy spectrum and wavefunctions as well as thermodynamical observables in (2+1)-dimensional quantum mechanics, and give an estimate of the statistical errors. Our numerical results are in good agreement with the exact ones.
• Select
  Multiple Soliton Solutions of the High Order Broer-Kaup Equations

  BAI ChengLin

  理论物理通讯. 2000, 34(4): 729-732.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Using the extended homogeneous balance method, which is very concise and primary, we find the multiple soliton solutions of the high order Broer-Kaup equations. The method can be generalized to dealing with high-dimensional Broer-Kaup equations and other class of nonlinear equations.
• Select
  Tensor Vacuum Susceptibility

  ZONG HongShi, HE HanXin, LÜ XiaoFu, ZHAO EnGuang

  理论物理通讯. 2000, 34(4): 733-736.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Using a nonlocal four-quark condensate in the framework of the modified global colour symmetry model, we determine the tensor vacuum susceptibility needed in the QCD sum rule external field method for the coupling of tensor current to hadron and compare it with the previous estimations.
• Select
  On the Spectrum of a (p, q)-Deformed Oscillator with a Kind of Nonlinear Interaction

  GONG RenShan

  理论物理通讯. 2000, 34(4): 737-740.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Spectrum of a (p,q)-deformed oscillator interacting with a classical current via intensity-dependent field operator is investigated by means of the factorization method. It is shown that the spectrum in this case is similar to the one ofq-oscillator with a linear interaction; but the discrete spectrum consisting of a finite number of levels with infinite multiplicity may appear only when the parameters still satisfy a couple of additional conditions.
• Select
  Entangled Eigenvectors of Scalar Fields φ₁(x) - φ₂(x) and П₁(x) + П₂(x)

  FAN HongYi, CHEN ZengBing

  理论物理通讯. 2000, 34(4): 741-744.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  We first demonstrate the precise Einstein-Podolsky-Rosen entanglement, which is inherent in quantum mechanics, in the context of quantum theory of complex scalar fields. We explicitly derive the entangled common eigenstates of φ₁(x) - φ₂(x) and П₁(x) + П₂(x) φ₁and φ₂ are two real components of the complex scalar field, and П₁ and П₂ are the corresponding conjugate fields) in the Fock space. The entangled eigenstates span a complete and orthonormal representation.