1998年, 第29卷, 第1期　
刊出日期：1998-01-30

  

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  One-Dimensional Interacting Fermions with Two Scatterers

  Nabeel Saleh NASSER, ZHANG Yumei, CHEN Hong, WU Xiang

  理论物理通讯. 1998, 29(1): 1-6.

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  The low-energy behavior of the one-dimensional spinless interacting fermions under the effects of two local scatterers is investigated via the bosonization technique and the Gaussian variational ground state. The renormalized mass is evaluated and the phaie diagrams are compared with those of the one-scatterer model.
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  Effect of Intersubband Coulomb Interaction on Hot-Electron Transport in Two-and One-Dimensional Electron Systems

  DONG Bing, LEI Xiaolin

  理论物理通讯. 1998, 29(1): 7-12.

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  We study the hot-electron transport properties of model GaAs-based quasi-two-dimensional(-quantum-well) and quasi-one-dimensional'(quantum wire) systems having two occupied subbands by using the Lei-Ting balance-equations for two types of carriers. Both the intersubband electron-phonon interaction and intersubband Coulomb interaction are taken into account. Our numerical results show that when the electron density is high enough, the intersubband Coulomb interaction is substantially strong in thermalizing the electrons between the different subbands. As a consequence, the one-type-of-carriers model (OTCM) is a good approximation for electron transport. However, in the cases of the lower electron densities, the intersubband Coulomb interaction is not strong enough to fire the electrons in differents-ubbands to share a common electron temperature and a more accurate two-types-of-carriers model (TTCM) must be used for analysis.
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  On Calculation of R-Line Thermal Shift of MgO:V²⁺

  MA Dongping, CHEN Jurong, LIU Yanyun

  理论物理通讯. 1998, 29(1): 13-18.

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  The mistakes in Ref. [3] are pointed out. Some important problems are discussed, and the correct ideas, calculations and results are given. The R-line thermal shift of MgO:V²⁺ at normal pressure is the algebraic sum of the contribution from electron-phonon interaction and the contribution from thermal expansion. The latter can be calculated by using the thermal expansion coefficient and the pressure-induced shift.
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  Numerical Solution of the Four-Anyon Problem

  RUAN Wenying

  理论物理通讯. 1998, 29(1): 19-24.

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  By making use of the Talmi-Moshinsky transformation bracket, -the Schrödinger equation for four anyons in configuration space has been solved variationally to obtain the eigenenergies and eigenfunctions. The low-lying states have been presented as functions of the statistical parameter. We illustrated how the bosonic states evolve continuously into the fermionic states.
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  Electronic Energy Loss and Straggling of Protons in Metals

  WANG Nengping, HO Yukun

  理论物理通讯. 1998, 29(1): 25-32.

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  By making use of the linear-response dielectric theory and local electron density approximation, we calculate the electronic stopping cross section and energy straggling. of protons in metals. The correlation and exchange interaction of electron gas in metals is taken into consideration by introducing a local-field-correction function.in the dielectric function. The theoretical results are compared with experimental and empirical data, as well as with other previous theoretical results.
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  Relativistic Quantum Statistical Aharonov-Bohm Effect of Many-Boson System in Mesoscopic Ring

  ZHAO Hongkang

  理论物理通讯. 1998, 29(1): 33-42.

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  The relativistic quantum ktatistical properties of charged many-boson system with rest mass mo for each boson confined in a mesoscopic ring are investigated. The small ring is threaded by Aharonov-Bohm magnetic flux ф. At low temperature, m₀ > K_BT, we have performed analytical calculations starting from evaluating the logarithm of grand partition function by using Mellin transform. The pair-production problem is excluded from our consideration for the temperature is low. The number density, total energy, specific heat and persistent current are obtained in general. These thermodynamic functions oscillate periodically in ф with period ф₀ = h/q, and they are related to the modified Bessel functions of the second kind K_v(γ) The chemical potential μ is restricted by μ< m₀ to ensure the positive number density of particles and the convergence of fugacity expansions. We find that these functions decay exponentially with temperat hre, and they also decrease as the circumference L increases. The non-relativistic and ultra-relativistic behaviors of these functions are discussed by considering the asymptotic behaviors of K_v(γ). There is no Bose-Einstein condensation in this system.
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  From Dynamics to Statistical Mechanics:the Two-Hard-Disk Model

  ZHENG Zhigang, HU Gang

  理论物理通讯. 1998, 29(1): 43-50.

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  The ergodic and mixing behaviors of the two-dimensional two-hard-ball systems are numerically investigated. Ergodicity and equipartition of energy are numerically explored for different inertial mass cases. The evolutions of the Boltzmann's entropy and the averaged energy are discussed, and the long time tail behavior of the Boltsmann's entropy is found and its origin is heuristically revealed.
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  Controlling Dynamical System to Variety of Goals

  ZHDU Changsong, CHEN Tianlun

  理论物理通讯. 1998, 29(1): 51-58.

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  A general method for controlling dynamical system to various desired goal dynamics is proposed. The convergent condition of the coptrol is suggested analytically.A technique of introducing "traasient" goal allows the control to be switched on at any time, and the system quickly conforms to the goal closely,almost without transient, resulting in only very small perturbations to the system parameter. The effciency and superiority of the method is illusrated by simulations on logistic map and Henon map. This method enables dynamical system to operate in a much wider variety of situations than that originally desgned.
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  Finite-Size Effects on the Phase Diagram and Evolution of Strangelets in Ultrarelativistic Heavy-Ion Collisions

  HE Yongbin, CHAO Weiqin, GAO Chongshou, LI Xueqian

  理论物理通讯. 1998, 29(1): 59-64.

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  In the framework of multiple reflection expansion, finite-size effects are incorporated into the study of the phase diagram and evolution of a strangelet in equilibrium with a finite hadronic phase. It is found that in a significant way finite-size effects can modify the phase diagram and reduce the survival probabilities of cold strangelets in ultrarelativistic heavy-ion collisions. The inclusion of finite-size effects can also allow a quantitative analysis of the properties of a cold strangelet resulting from a smooth hydrodynamic evolution with equilibrium hadronization and isentropic expansion.
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  The Structure of the Neutron-Rich Nd Isotopes in the IBM

  LONG Guilu, ZHU Shengjiang, ZHANG Jinyu, ZHAO Enguang, LIU Yuxin

  理论物理通讯. 1998, 29(1): 65-72.

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  The spectra and E2 transition properties of ^146-156Nd isotopes are studied in the interacting boson model in the light of new experimental data. It is found that ^146-150Nd are in the transition from the vibrational limit to the rotational limit. From ¹⁵²Nd onward, the isotopes are nearly perfect rotors. Possible deformation saturation is discussed in the interacting boson model.
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  The Effects of Isoscalar MEC and Six-Quark Cluster on W₁/W₂ of the Deuteron

  CHENG Tansheng, ZHONG Yushu, LU Lanchun

  理论物理通讯. 1998, 29(1): 73-80.

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  The ratio of the deuteron structure function W₁/W₂ in deuteron electrodisintegration in the threshold region has been calculated by using the hybrid quark-hadron model, including isoscalar MEC. Our investigation shows that isoscalar MEC and six-quark cluster have large effects on W₁/W₂.
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  Study of the Binding Energy of Relativistic Nuclear Matter in the Relativistic σ-ω-π Model

  LIU Lianggang, CHEN Wei

  理论物理通讯. 1998, 29(1): 81-86.

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  A relativistic σ-ω-π model is proposed to calculate the binding energy of relativistic nuclear matter. We put emphasis on the relativistic particle-hole, delta-hole excitation of pion propagator in nuclear matter. The renormalization of the nucleon self-energy in nuclear matter is made for the pseudo-vector πNN and πNΔ couplings by introducing corresponding form factor and by dispersion relation. We find that the density dependence correction to meson-NN coupling constants is very important to saturate the binding energy of nuclear matter. The density dependence correction to πNN and πNΔ coupling constants has the effect of softening the EOS of nuclear matter.
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  Intermittency or Something Else in High Dimensions

  GAO Chongshou, HE Bin

  理论物理通讯. 1998, 29(1): 87-92.

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  A regular two-particle correlation function is proposed to explain the intermittency behavior in pp collision at √3= 630 GeV. It is found that the intermittency behaviors in all dimensions in the experiments can be reproduced with a regular two-particle correlation function. Maybe the existence of intermittency in a serious sense in high dimensions is still a puzzle and the factorid moments of order-two would saturate in the limit of small bin sizes of phase space in high dimensions at last.
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  The Standard Model with Higgs as Gauge Field on Fourth Homotopy Group

  GUO Hanying, LI Jianming, WU Ke

  理论物理通讯. 1998, 29(1): 93-98.

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  Based upon a fundamental principle, the generalized gauge principle, we construct a general model with G_L×G'_R×Z₂ gauge symmetry, where Z₂ = π₄(G_L) is the fourth homotopy group of the gauge group G_L, by means of the non-commutative differential geometry and reformulating the standard model with the Higgs field being a gauge field on the fourth homotopy group of their gauge groups. We show that in this approach not only the Higgs field is automatically introduced on an equal footing with ordinary Yang-Mills gauge potentials and there are no extra constraints among the parameters at the tree level but also most importantly the models survive quantum corrections.
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  Resolved Photoproduction of J/ψ at HERA

  LI Yunde, LIU Lianshou

  理论物理通讯. 1998, 29(1): 99-104.

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  The J/ψ photoproduction via resolved photon process at HERA is studied. It turns out that the J/ψ production is dominated by the leading order production process in low pt range (p_t < 4 GeV), while in the high pt range (p_t > 4 GeV), it is dominated by the fragmentation processes. The difference of J/ψ cross section caused by using GRV and DO photon structure functions is large, especially in the large negative rapidity range. Hence it is possible to use the J/ψ photoproduction process to probe the parton distribution of photon and proton, as well as to test the gluon and heavy quark fragmentation of J/ψ from the perturbative QCD.
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  Completeness Relation of the SU(3) Charged and Hypercharged Coherent State

  FAN Hongyi, WEI Hua, ZOU Hui

  理论物理通讯. 1998, 29(1): 105-110.

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  Using the MelJin inversion formulas we derive the weight function for constructing the completeness relation of the boson SU(3) charged and hypercharged coherent state. A suitable contour integration is selected for this derivation.
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  Intrinsic Regularization Approach to Chiral Anomalies

  CAI Yu, GUO Hanying

  理论物理通讯. 1998, 29(1): 111-124.

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  With the help of the intrinsic regularization method, we present a new method which enables us to calculate the chiral anomalies in a much natural and self-consistent way. By checking Ward iden tities related to various.diagrams involving anomaly, we analyze anomalies in the σ model, in Abelian gauge theory, and in non-Abelian gauge theory as well. Our calculations prove to naively preserve all vector Ward identities and accordingly reproduce the famous ABJ-anomaly with no need of introducing any counterterms.
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  The Dynamo-Driven Magnetic Helicity Transport

  X. M. QIU, A. K. WANG

  理论物理通讯. 1998, 29(1): 125-132.

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  In this paper, a new set of the evolution equations for the helicity of the mean magnetic field and the mean helicity of the fluctuating magnetic field is derived from the Maxwell equations and the generalized Ohm's law with the dynamo action. It is shown that there exist two kinds of the dynamo-driven magnetic helicity transport. One of them makes the mean magnetic field helicity transfer to the fluctuating magnetic field, yielding an anomalous loop voltage. The other makes the fluctuating magnetic field helicity transfer to the mean magnetic field, which provides a convincing evidence for the existence of the dynamo current. Therefore, the two kinds of the magnetic helicity transport describe the mutual conversion between the regular and irregular motions. The formulas of the loop voltage and the dynamo current are given. In particular, we give out the formula of the dynamo current-generated equilibrium magnetic field which provides a concrete mode of the magnetic field creation and maintenance in both astrophysical and laboratory (e.g., reversed-field pinch) plasmas.
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  Relativistic Beaming in Gamma-Ray Bursts

  SHI Tianyi, XU Dawei

  理论物理通讯. 1998, 29(1): 133-138.

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  Relativistic beaming effect is an important radiation mechanism in explaining gamma-ray bursts, according to recent observed data by Compton Gamma-ray Observatory (CGRO). Pair production optical depth and relationship between Lorentz factor and spectral index have been calculated in considering non-uniform distribution of beam photons in gamma-ray bursts in this paper. As a comparison, we also calculate the minimum Lorenta factor for 54 observed gamma-ray bursts by CGRO.
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  The Quantization of Mesoscopic Electric Circuit with the Discreteness of Electron Charge

  LI Youquan, CHEN Bin

  理论物理通讯. 1998, 29(1): 139-142.

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  The importance of discreteness of electron charge for mesoscopic electric circuit is addressed. A quantization bf the circuit in accord with the discreteness of electric charges is proposed, and a Schrödinger equation incharge representation'is obtained. The Schrödinger equation is turned to be Mathieu equation in'current representation', the wavefunction and energy spectrum can be solved exactly. The WKB solutions of the energy levels for the ground state and the excited states are given.
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  Validity and Limitation of Semi-Classical Approaches to Giant Magnetoresistance in Magnetic Multilayers

  SHI Yu

  理论物理通讯. 1998, 29(1): 143-144.

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  The validity and limitation of semi-classical theories on giant magnetoresistance in magnetic multilayers are discussed on the basis of fundamental quantum statistical mechanics.
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  Broer-Kaup Systems from Darboux Transformation Related Symmetry Constraints of Kadomtsev-Petviashvili Equation

  LOU Senyue, HU Xingbiao

  理论物理通讯. 1998, 29(1): 145-148.

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  Using the Darboux transformation related symmetry constraints of the Kadomtsev-Petviashvili (KP) equation, we get some integrable (1+1)-dimensional and (2+1)-dimensional multi-component Broer-Kaup (BK) systems.
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  q-Deformed Differential Operator Superalgebra on Quantum Superplane

  WANG Hong, WANG Luyu, ZHAO Weizhong

  理论物理通讯. 1998, 29(1): 149-152.

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  The q-deformed differential operator superalgebra is proposed, and these differential operators are analyzed in the framework of quantum superplane. At the same time, a solution of graded Yang-Baxter equation is obtained.
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  Symmetry Reductions and Integrability for the Modified Boussinesq Equation from EPU Problem

  QU Changzheng

  理论物理通讯. 1998, 29(1): 153-156.

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  In this paper, we discuss symmetry reductions of the modified Boussinesq equation arising in the Fermi-Pasta-Ulam problem, which is used to investigate the behaviour of systems which are primarily linear but a nonlinearity is introduced as a perturbation by using the direct method due to Clarkson and Kruskal. A symmetry group theoretical explanation for the results is provided. We conclude that the modified Boussinesq equation is not integrable.
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  Superconductivity and Temperature Effects on Davydov Model of α-Helix Protein

  ZHANG Lingyun, LIN Jiatih, LI Bozang, PU Fucho

  理论物理通讯. 1998, 29(1): 157-160.

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  We study the thermodynamic properties of α-helix protein on the basis of Davydov theory. The Hamiltonian of Davydov theory can be represented as a form of pairing Hamiltonian in the momentum space. We prove that the quasi-classical Davydov theory is essentially a theory with Bose condensation no matter whether the molecular excitations are treated as fermions or bosons. The transition temperature of superconductivity theory gives the existence condition of the Davydov soliton.