1992年, 第18卷, 第1期　
刊出日期：1992-07-30

  

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  Critical Behavior of an NNN Interaction Model

  Hai-Yan ZHANG and Bo-Wei XU

  理论物理通讯. 1992, 18(1): 1-6.

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  A one-dimensional quantum mode1 with generalized next-nearest neighbour interaction is studied. The numerical results convince us of the existence of critical phenomenon in this model. The critical point condition is given, and the model belongs to the Ising universality.
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  Polaronic States Incorporating Effects of Phonon Confinement in a Rectangular Quantum Well Wire

  Ka-Di ZHU, Shi-Wei GU

  理论物理通讯. 1992, 18(1): 7-14.

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  The electron self-energy due to the interaction of the electron with the LO-phonon incorporating effects of phonon confinement in a rectangular quan tum well wire has been calculated as a function of the size of the wire by the perturbative method within the framework of the effective mass approximation. The results show that in a very smaU wire the self-energy has a peak at the beginning and then increases gradually to the two-dimensional limit value as the wire expands in one direction while keeping fixed in the other direction. The peak values are about at the square cross sections. For larger wires, the self-energy increases monotonically without appearing peaks and approaches slowly to the two-dimensional limit values. The results also present that the self-energy is related to the size of the cross section rather than to the cross sectional area of the wire, and the absolute values of the self-energies are lese than those in comparable two-dimensional quantum wells.
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  The Electron-Lattice Coupling in Quasi-One-Dimensional Halogen-Bridged Mixed-Valence Platinum Complexes (HMPC's)

  Jing-Cui PENG

  理论物理通讯. 1992, 18(1): 15-18.

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  The effect of site-diagonal and site-off-diagonal electron-lattice coupling on polaronic binding energy in quasi-one-dimensional halogen-bridged mixed-valence platinum complexes (HMPC's) is investigated. It shows that the site-diagonal part is determinative in this kind of material, and agreeable with experiments.
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  Generalized Nonlocal Ginzburg-Landau Equations

  Hong-Hua XU, Xiao-Xing HU, Chien-Hua TSAI

  理论物理通讯. 1992, 18(1): 19-26.

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  In a previous paper we established a set of nonlocal Ginzburg-Landan equations near T_c. In this paper this set of equations is generalized to the cases well below T_c. the generalization is characterized by two new kernel functions which can be reduced to a similar form aa that obtained previously. The form factor resulted from first principle calculation is in good agreement with neutron scattering data.
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  Second Virial Coefficient of Anyons with Spins

  Shun-Qing SHEN, J. CAI, Rui-Bao TAO

  理论物理通讯. 1992, 18(1): 27-32.

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  We study the statistical properties of a two-dimensional gas of free anyons with spin. The concept of "spin" carried by anyons has been discussed in detail based on the twodimensional Dirac equation. The second virial coefficient B₂ for the gas is evaluated and is found that it is the result of Arovas et al^[1]. but not the result of Blum et al^[2]. that is recovered, which is periodical for the statistical parameter α with the length Δα = 2.
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  Cooperative Jahn-Teller Effects and Structural Instability instability La_2-xM_xCuO₄(M=Ba, Sr)

  Jian-Bin WU and Wen-Zhou LI, He-Ping YING and Jian-Bo ZHANG

  理论物理通讯. 1992, 18(1): 33-40.

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  In this paper, the effective Hamiltonian for lattice vibration was calculated through the aseumption of competition between cooperative Jahn-Teller effects and electron-electron correlation. The soft modes at the zone-center and their relations with the structural phase transitions in La_2-xM_xCuO₄(M=Ba, Sr) were studied.
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  Topological Action for One-Dimensional Antiferrornagnet as Superposition of Berry's Phase for Coherent States

  Lin PANG, Chan-Pu SUN, Mo-Lin GE

  理论物理通讯. 1992, 18(1): 41-48.

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  A new complete set of spin coherent states is constructed and applied to study the time evolution matrix of one-dimensional antiferromagnet by means of the path integral method. A topological term expressed as the superposition of the Berry's phase of individual site is obtained. The superposition is not the Berry's phase of the system but the A-A phase of the spin chains, and the equation obtained by our path integral method is consistent with that given by others.
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  A Soliton Perturbation Theory for the MNLS Equation with Corrections in terms of an Auxiliary Spectral Parameter

  Zong-Yun CHEN, Nian-Ning HUANG

  理论物理通讯. 1992, 18(1): 49-58.

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  Based on the lakharov-Shabat equation of the inverse scattering transform for the MNLS equation, a perturbation theory for the MNLS equation with corrections is developed in terms of an auxiliary spectral parameter ζ. All necessary formulae for calculating the scattering data are derived without any assumption beyond the usual conditions for the inverse scattering transform. Based upon these formulae, the effects due to the corrections can be calculated.
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  Yang-Baxterization of Spin-1 L Operator

  Mo-Lin GE and Xu-Feng LIU

  理论物理通讯. 1992, 18(1): 59-64.

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  The Yang-Baxterisation of L operator is performed for spin-1 model, namely, for given braid group representation (BGR) the x-dependent L(x) operator can be determined where x is the spectral parameter. It is pointed out that in order to establish such an x-dependence besides the usual L_± operators in accordance with the Faddeev-Reshetikhin-Takhtajan (FRT) approach an additional operator L₀ should be introduced. The explicit expression of L₀ is given. This Yang-Baxterisation prescription preserves the FRT and the YBE is satisfied by L(x) and R(x).
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  NN Spin-Orbit Force in Quark Model

  Xiao-Ming XU and Xi- Jun QIU

  理论物理通讯. 1992, 18(1): 65-74.

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  A chiral quark-soliton model with the gluon field and chiral fields (σ, π and ω) is employed to study the NN spin-orbit potential within a relativistic twoquark-cluster theory. The effective NN spin-orbit potential generated by the one-gluon exchange decreases with the increase of energy. It is as important as one a-meson exchange and one w-meson exchange and is close to the spin-orbit splitting in nuclei.
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  The Origin of the EMC Effect

  Hong-Qing SHEN and Jian-Jun YANG, Guang-Lie LI

  理论物理通讯. 1992, 18(1): 75-80.

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  In this paper, using the idea of nucleon swelling in nucleus, we discuss the Q²- and x-rescaling on the nucleon structure function for explaining the EMC effect, and find that the parton evolution produced by nucleon swelling in the nuclear medium may be the origin of the EMC effect.
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  CP Asymmetries in Two-Body Baryonic Decays of B_d⁰ - B_d⁰ System

  Jia-Fu LIU, Ling-De WAN and Gong-Ru LU

  理论物理通讯. 1992, 18(1): 81-86.

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  The partialdecay-rate asymmetries indicating the CP violating effects in two-body baryonic decays of B: - B: eystem are systematically studied. It turns out that the CP asymmetries are large in some processes, 1.6×l0⁸, 5.5×l0⁹ and 4.2 x 10⁹ bb pairs are needed for testing the CP violation in B_d⁰ - B_d⁰ → pp, Δ⁰Δ ⁰ and Δ⁺⁺Δ ⁺⁺, respectively. It is impossible to detect the CP violating effects in those decays where penguin diagrams dominate.
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  The Implication of Kamiokande-Ⅱ Sun Neutrino Data

  Yi-Shi DUAN and Feng-Cai MA

  理论物理通讯. 1992, 18(1): 87-90.

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  The cross section of B solar neutrino scattering involving the contribution of neutrino magnetic moment (NMM) is investigated. The constraints on the probability of flip of neutrino helicity and the possible value of NMM are extracted from the Kamiokande-II solar neutrino data and calculated cross section of v_e, scattering. It is found that the probability of neutrino helicity flip allowed by the Kamiokande-Ⅱ data may be small, which would be difficult to understand the ³⁷Cl data.
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  Final State Interaction and the W-Exchange Diagram

  Xue-Qian LI, Tao YU

  理论物理通讯. 1992, 18(1): 91-104.

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  We employ the Isgur et al. method to evaluate the contribution from the final state interactions to D⁰→ KK and ππ explicitly, then determine the contribution from the W-exchange diagram. We found that the new measurements confirm the smallness of the W-exchange contribution, but indicate that it may have a complex phase relative to the spectator diagram.
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  Intralayer and Interlayer Couplings in the Soliton pairing Model of Superconductivity

  Yong-Li MA, Xian-Xi DAI

  理论物理通讯. 1992, 18(1): 105-108.

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  Explicit expressions and results for T_c(n) of the layer compounds of Bi and T1 are obtained within the generalized soliton pairing framework, in which T_c, is raised by the cooperation l i of the two couplings, intralayer and interlayer. The calculated values are in good agreement I with the observed T_c's. The maximum possible T_c(∞) is predicted at≈ 200 K.
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  Another Possible Phenomenological Model of the Normal State of the High-T_c Oxide Superconductors

  Jin-Ming DONG and D.Y. XING, M. LIU

  理论物理通讯. 1992, 18(1): 109-112.

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  A new phenomenological model has been proposed to account for the anomalous normal state properties of the high-T_c, oxide superconductors. Comparison with the assumed one in the marginal Fermi liquid theory is made. Both of them are similar, but also different. It is shown that in a small frequency region of ω < T (T being the temperature), the conventional Fermi liquid picture still holds, while for ω > T the marginal Fermi liquid theory is appropriate.
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  Affine Super Toda Theories as Reduced WZNW Model

  L. CHAO

  理论物理通讯. 1992, 18(1): 113-118.

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  The afllne euper Toda theoriea are obtained by imposing second order constraints on the eupergroup-valued WZNW model. The reduction is Hamiltonian so that one can get various properth of affine euper Toda eystem from that of WZNW model.
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  The Phase Structure of Lattice U(1) Gauge Theory with Radially Fixed Higgs Fields: An Analytical Analysis

  J.M. YANG

  理论物理通讯. 1992, 18(1): 119-122.

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  In this letter, the variational cumulant expansion t extended to the d-dimensional U(1) gauge theory with radially fixed Higgs fields. The pharre structures are given for d = 4 and d = 3 cases. The comparison with the Monte Carlo and mean field results is abo presented.
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  W-T Identities, Normalization of the BS Wave Function and Properties of the Pion

  Yuan-Ben DAI and Chao-Shang HUANG, Yi-Bing DING, Chui-Lin WANG, Yun-Lun ZHU

  理论物理通讯. 1992, 18(1): 123-128.

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  We discuss some problems concerned with the normalization of the BS wave function in connection with Ward-Thkahashi identities in the Lorentz covariant Bethe-Salpeter formalism proposed in the previous work. Physical quantities of the pion as a Goldstone boson, including the π⁰ → 2γ amplitude are calculated in the QCD motivated models and results are in agreement with the experimental data.