1996年, 第25卷, 第3期　
刊出日期：1996-04-30

  

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  A Numerical Method for the Calculation of Transmission Coefficient

  Meng-Li DU

  理论物理通讯. 1996, 25(3): 257-260.

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  A numerical method is presented for calculating the quantum-mechanical transnmission coefficient of one-dimensional problems with potentials of arbitrary shapes. The method is demonstrated to give very accurate results on two solvabie examples. The numerical error in the calculated transmission coefficient is proportional to the second power of integration step size for potentials without discontinuities; for potentials with discontinuities, the dependence is linear.
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  The Quantum Motion of an Ion in a Combined Trap

  Xiao-Chun GAO, Jun GAO, Jian FU

  理论物理通讯. 1996, 25(3): 261-268.

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  The invariant formulation is used to investigate the quant um motion of an ion in a combined trap. The classical correspondence of the quantum motion and stability problem are then discussed.
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  Phase Transition in Two-Dimensional Classical Coulomb Plasma by Mapping to Quantum sine-Gordon System in Euclidean space

  Zhi-Jian CHEN, Yu-Mei ZHANG, Bo-Wei XU

  理论物理通讯. 1996, 25(3): 269-276.

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  The phase transition of the two-dimensional (20) Coulomb plasma is studied with the help of the equivalence to a quantum sine-Gordon system in 2D Euclidean space. The minimum and the stability of the grand canonical potential are derived by making use of the variational effective potential method. The phase diagram thus obtained shows a larger region of plasma phase in the parameter plane than the parallel result in the (l+l)-dimensional Minkowski space. The origin of this difference is discussed in connection with the manner of the large momentum cut off being taken.
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  Spin Wave Spectra of Ferromagnetic Superlattice with Antiparallel Magnetization

  Yong-Qiang WANG, Zhen-Ya

  理论物理通讯. 1996, 25(3): 277-282.

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  In this paper, by using the Holstein-Primakoff (HP) and Bogoliu bov transformation, the spin wave spectra of ferromagnetic/nonmagnetic superlattice with antiparallel magnetizations between the neighboring ferromagnetic films are studied. The effects of some magnetic parameters on the spin wave spectra are discussed in detail.
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  Fractal Aggregation with Next-Nearest Neighbor Interactions in External Fields

  Ju-Ping TIAN, Bo-Ming YU, K. L. YAO

  理论物理通讯. 1996, 25(3): 283-288.

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  In this paper, we present a particle-cluster model for a two-dimensional fractal aggregation with the nearest neighbor and next-nearest neighbor interactions in external fields. The external field is described by the probability P. Our computer simulation results show that the threshold concentration is P_c^a = 0.59 ± 0.02 and the fractal dimension is D_c = 1.67 ± 0.03 at this concentration. In comparison with previous results with nearest neighbor interaction only, we find that D_c is the same, but P_c^a is smaller, which is reasonable, since the connectivity has been changed significantly.
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  Critical Phenomena in Systems with Pseudo-Long-Range is Disorder

  X. T. WU, Z. Q. HUANG

  理论物理通讯. 1996, 25(3): 289-292.

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  Critical phenomena in systems with long(bu t finite)-range-correlated disorder of "random temperature" are studied. The disorder with correlation function g (k)~v + w/(p + k^d-a) (d is the spatial dimension) is considered. The critical behavior in an m-vector spin system with such a disorder is investigated by using renormalization-group expansion in ε = 4 - d and δ = 4 - a. The recursion relations of coupling constants for (T > T_c) are obtained. It is shown that critical phenomena in systems with such a pseudo-long-range disorder will exhibit crossover from tricritical to critical behavior for a < d. In the crossover regime the scaling relations are expected to break down.
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  Dynamics of Overlap in Pair-Correlated Hopfield Model

  Dao-Yun JI, Bei-Lai HU, Tian-Lun CHEN

  理论物理通讯. 1996, 25(3): 293-298.

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  The first step evolution of main overlaps in the pair-correlated Hopfield network is calculated by an analytical approach with probability theory, the results are in good agreemen t with computer simulations. On the basis of some assumptions, we obtain the final value of main overlaps at t = ∞, from which three regimes in parameter space, pattern-retrieval, pairretrieval and paramagnetic regimes, are discovered.
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  Three-Generat ion Models from Global Gauge Anomaly-Free Theories

  A. E. F. Djemai

  理论物理通讯. 1996, 25(3): 299-306.

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  In this work, we show how a global gauge anomaly of a gauge group H can be computed from a local one of a larger gauge group G ⊃ H. We also show that the number f of generations is tied to the consistency of a gauge theory H with initially a Z_f gIobal gauge anomaly. We give some examples of SU(N) models, in different dimensions of spacetime, with three families.
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  The Multicomponent Coherent States of the Lie Algebra SO(4)

  Guang-Hua LI

  理论物理通讯. 1996, 25(3): 307-312.

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  The multicomponent coherent states associated with the Lie algebra SO(4) are presented. An inhomogeneous differential realization of SO(4) in this multicomponent coherent state space is obtained.
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  Relativistic Particle-Hole and Delta-Hole Excitations for Pion Propagator in Nuclear Matter

  Liang-Gang LIU, W. H. MA, H. C. CHIANG

  理论物理通讯. 1996, 25(3): 313-318.

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  The relativistic particle-hole and delta-hole polarization insertions for pion propagator are calculated by using particle-hole-antiparticle representation of nucleon and delta propagators in nuclear matter. The short-range correlations between nucleon-nucleon, nucleon-delta and delta-delta are included via Landau-Migdal parameter g' in the random phase approximation. We calculate the dispersion relations for pions and find out that the damped pion condensation is removed by the short-range correlation and there is a long gap in the dispersion relation.
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  Compression Properties of Finite Nuclear Matter at Zero and Finite Temperatures with the Skyrme Force SKM

  Neng-Ping WANG, Shan-De YANG, Yu-Kun HO

  理论物理通讯. 1996, 25(3): 319-326.

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  By taking into account the finite-size effect rationally in the framework of the Hartree-Fock theory, compression properties at zero and finite temperatures of finite nuclear matter are investigated with the Skyrme force SKM^*. Energies of the isoscalar giant monopole resonance of nuclei at zero temperature calculated are found to be in agreement with experimental and empirical values.
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  The Average Nucleon Density in Intrinsic State of FDSM SO(6)

  Lian-Ao WU, Xiao-Gong JING

  理论物理通讯. 1996, 25(3): 327-334.

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  The average nucleon density in the intrinsic state of SO(6) of the fermion dynamical symmetry model is given. The relation between the geometric model and the fermion dynamical symmetry model is established microscopically in terms of the bridge of the nucleon density. An approximate expression of deformed parameters in the geometric model is obtained analytically by comparing the nucleon density of the fermion dynamical symmetry model with that of the geometric model.
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  Analytical Calculation of Critical Exponent in U(1) Lattice Gauge Theory

  Xi-Te ZHENG, Yuan HE, Zhao LU

  理论物理通讯. 1996, 25(3): 335-338.

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  The critical exponent b of lattice gauge theory in (3 + 1)-dimension is calculated by using approximate analytical results of (L) in the deconfining phase transition region. The obtained b = 0.3622 ± 0.0027 confirms the universality conjecture. An extrapolating approach to determine the deconfining phase transition point is proposed.
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  The Spectra of the Light 0⁺⁺ Mesons in QCD Sum Rules

  Jue-Ping LIU, Dun-Huan LIU, Chao-Hsi CHANG, Xue-Qian LI

  理论物理通讯. 1996, 25(3): 339-346.

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  In this work, the fight J^PC = 0⁺⁺ mesons f₀(975), a₀(980) and S^*(980) are interpreted as the usual qq states, their masses are investigated in the framework of the QCD sum rules.
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  Comments on QCD Corrections to b + sγ Decay

  Cai-Dian LU, Jing-Liang HU, Chong-Shou GAO

  理论物理通讯. 1996, 25(3): 347-352.

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  We find some errors in the previous calculation of leading log QCD corrections to b + sγ decay, which include corrections from mto, to M_w in addition to corrections from M_w to m_b. The inclusive decay rate is found to be enhanced more than previous calculations. At m_t = 170 GeV, the running from m_top to M_w results in 13% enhancement, and for m_t = 250 GeV, 16% enhancement is found.
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  Hamiltonization of the Singular Systems with Hessian Variable Rank

  An-Min WANG, Tu-Nan RUAN

  理论物理通讯. 1996, 25(3): 353-360.

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  The difficulties in Dirac's algorithm of Hamiltonization are discussed. By comparison of Sudarshan and Mukunda's approach dealing with the singular systems with Hessian variable rank, we study in detail the validity, application and presupposition of our extended Dirac's consistency conditions. It is given and shown that the Hamiltonization of thegeneral singular systems with the varying rank Hessian matrix can be carried out by the algorithm of the extended Dirac's consistency conditions.
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  Theoretical Study of Deflection of Reflected and Refracted Electromagnetic Waves from Incident Plane

  Xin-Ya LIU

  理论物理通讯. 1996, 25(3): 361-364.

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  An equation for the orbital angular momentum of electromagnetic waves in the process of reflection and refraction is deduced from the generalized variational principle, which shows the transverse shift of reflected and refracted waves and predicts that the deflection of reflected and refracted waves from the incident plane can occur.
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  Gauge Transformation and Generalized Nonlocal Symmetries of the Korteweg-de Vries Equation

  Sen-Yue LOU

  理论物理通讯. 1996, 25(3): 365-368.

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  After extending the usual Lax pair of the Korteweg-de Vries (KdV) equation to a generalized form by using a gauge transformation, an adjoint Lax pair of the KdV equation is introduced. With the help of the spectral functions of the Lax pair and the adjoint Lax pair, a new nonlocal seed symmetry (which is gauge-invariant) is found and then a set of new infinitely many generalized nonlocal symmetries are obtained after establishing a general symmetry theory for an arbitrary nonlinear system.
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  Symmetry Algebras of Generalized (2 + 1)-Dimensional KdV Equation

  Chang-Zheng QU

  理论物理通讯. 1996, 25(3): 369-372.

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  Generalized symmetries with arbitrary functions of time t for the generalized (2 + 1)-dimensional KdV equation was founded by establishing a formal theory of obtaining the solution of one type of higher dimensional PDEs due to LOU (Refs [6]-[9l). These symmetries constitute an infinite dimensional Lie algebra which is a generalization to the well-known wo3 algebra. Obviously, the corresponding symmetry algebra is isomorphic to that of the Kadom tsev-Pe tviashvili (KP) equation.
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  Differential-Form Relations Between Density Operators and Their P-Representations in Coherent State Basis

  Hong-Yi FAN, Zhong-Xi ZHANG

  理论物理通讯. 1996, 25(3): 373-376.

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  By virtue of the technique of integration within an ordered product of operators, we derive differential-form relations between density operators and their P-representations in the coherent state basis. Some applications of these new relations in normally ordering operators are given.
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  Microscopic Studies on the Nucleus ²⁸O

  Zhong-Zhou REN, Bao-Qiu CHEN, Zhong-Yu MA, Gong-Ou XU

  理论物理通讯. 1996, 25(3): 377-380.

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  The ground-state properties of the nucleus ²⁸O are studied in relativistic and nonrelativistic mean-field approaches. It is shown by these calculations without any adjusting parameters that ²⁸O is a weakly bound nucleus and exhibits neutron halos. The differences among various mean-field approaches have been compared and discussed.
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  Analysis of ¹⁴C(π⁺, π^-) ¹⁴O Reaction at 50 MeV

  En-Guang ZHAO, Guo-Mo ZENG, Yu-Xin LIU

  理论物理通讯. 1996, 25(3): 381-384.

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  The ground states of ¹⁴C and ¹⁴O are described by a cluster wavefunction and the ¹⁴C_gs(π⁺, π^-) ¹⁴O_gs DIAS transition at 50 MeV is calculated in the Glauber theory. The results are in agreement with experimental data qualitatively and indicate that the effect of the l2 C core on the reaction is important.