理论物理通讯

Select

v =2/3 Edge State: A Toy Model Study from Composite Fermion Point of View

WEI HongDuo, YU Yue

理论物理通讯. 1999, 32(3): 321-326.

摘要 ( ) PDF全文 ( )

可视化

By using a toy model of the composite fermion excitations at edge states, we study the structure of the 2/3 edge state in fractional quantum Hall liquid. The electron density distribution is given by the numerical diagonalization method with the existence of an edge potential, either smooth or sharp one.

Select

Chaotic Behavior and Instability of Perturbed sine-Gordon Solitons

ZHANG ZeLan, ZENG LiBo

理论物理通讯. 1999, 32(3): 327-330.

摘要 ( ) PDF全文 ( )

可视化

Solitons of the sine-Gordon system interacting with a disturbed external field are handled by using a direct method. Theoretical analysis reveals that the single soliton perturbed by a periodic field leads to chaotic behavior of the system, and the perturbed double soliton is unstable for most of physically interesting spacetime disturbances.

Select

The Effective Gluon Propagator in the Global Color Symmetry Model

ZONG HongShi, Lü XiaoFu, SHEN CaiWan, CHANG ChaoHsi, ZHAO EnGuang

理论物理通讯. 1999, 32(3): 331-334.

摘要 ( ) PDF全文 ( )

可视化

It is shown that the effective gluon propagator in the global color symmetry model can be calculated in the instanton dilute liquid approximation. The calculated effective gluon propagator is consistent with the general command on the qualitative features of the gluon propagator, i.e., (i) the gluon propagator is significantly enhanced at small space-like k², and (ii) for k² > 1.5 GeV² the perturbative results are quantitatively reliable.

Select

Arbitrary Phase Rotation of the Marked State Cannot Be Used for Grover's Quantum Search Algorithm

LONG GuiLu, ZHANG WeiLin, LI YanSong, NIU Li

理论物理通讯. 1999, 32(3): 335-338.

摘要 ( ) PDF全文 ( )

可视化

A misunderstanding that an arbitrary phase rotation of the marked state together with the inversion about average operation can be used to construct a (less efficient) quantum search algorithm is cleared. The π rotation of the phase of the marked state is not only the choice for efficiency, but also vital in Grover's quantum search algorithm. The results also show that Grover's quantum search algorithm is robust.

Select

Analytical Study of the Layered XY Model with VCE Method

LIU ShiAn, WANG Qing, LI Hong, CHEN TianLun

理论物理通讯. 1999, 32(3): 339-344.

摘要 ( ) PDF全文 ( )

可视化

Motivated by experiments on liquid-crystal films, we study the development of specific heat anomaly of finite layer system. With the VCE method, we introduce the strong surface interaction into the layered XY model and get the results of the forth-order analytical expansion. The results show that when the strong surface interaction becomes strong enough, the order trend defeats the quantum noise and the specific heat peak moves abnormally to the high temperature with the number of layers decreasing.

Select

Spin-P honon Renormalization of the Excitation Energy in a Diluted Two-Dimensional Ferromagnet

XIONG Gang, WANG XiaoBing, ZHANG ZheHua, TIAN DeCheng

理论物理通讯. 1999, 32(3): 345-350.

摘要 ( ) PDF全文 ( )

可视化

The contribution of spin-lattice coupling to the phonon self-energy is calculated for a diluted two-dimensional "soft" ferromagnet. The calculations are based on a bond percolation model. Numerical results are presented for the dampings of phonon excitations. At low temperature, the damping rate is much smaller than the frequency of excitations, leading to well-defined phonons. The overall features of the Г ( q ) curves possess similar characteristics: Г ( q ) has two maximum points at qa ≈ 0.5 and qa ≈ 1.7, the value of the latter is much larger than the former. The temperature-dependent phonon line widths arising from spinlattice coupling are also presented. We point out the sensitivity of the interaction on bond concentration of the network.

Select

Origin of Spin Wave Gap in Metallic Ferromagnet La_1-χA_χMnO₃

Lü Pin

理论物理通讯. 1999, 32(3): 351-354.

摘要 ( ) PDF全文 ( )

可视化

The spin wave spectrum of the double-exchange model with anisotropic Hund coupling is investigated using the spin wave approximation and Green's function approach based on Furukawa's work [J. Phys. Soc. Jpn. 65 (1996) 1174]. It is found that there exists a spin gap, which agrees with the observations in the inelastic neutron scattering experiments for La_0.7Sr_0.3MnO₃ and La_0.7Pb_0.3MnO₃. The spin gap is directly related to the anisotropy of Hund coupling. The ratio of the xy and z Hund coupling strengths is estimated from experimental data and the possible origin of the spin gap from the Jahn-Teller effect is pointed out.

Select

Finite-Size Effects in Critical Phenomena from Mean-Field Approach with ф4 Model

YANG ChunBin, CAI Xu

理论物理通讯. 1999, 32(3): 355-360.

摘要 ( ) PDF全文 ( )

可视化

The finite-size effects in critical phenomena of a thin film system are studied from a mean-field (MF) approach with ф4 model for second-order phase transition. The influence of boundary condition on the critical properties is emphasized. Scaling functions for relative free-energy and relative specific heat are given.

Select

Influence of Scars on Time Averaged Ensemble Distribution of Quantum Cat Map in the Semiclassical Regime

WANG Jiao, GU Yan

理论物理通讯. 1999, 32(3): 361-366.

摘要 ( ) PDF全文 ( )

可视化

We study nonergodic behavior of an ensemble of quantum cat map with initially localized phase-space distributions. For this purpose, an amended version of the Wigner function on discretized phase torus is given, which shows meaningful classical-quantum correspondence in the semiclassical limit. We find the time averaged coarse-grained Wigner function is scarred and antiscared along some short periodic orbits, and the heights (depths) of these scars (antiscars) decrease linearly with h when the initial phase-space distribution is fixed and the semiclassical limit is taken by letting h = 1 / ( 2 π N ₀ b ⁱ ) with b a prime and ι → ∞.

Select

Clustering Behavior in Globally Coupled Rotator Systems

ZHENG ZhiGang, LI XiaoWen

理论物理通讯. 1999, 32(3): 367-374.

摘要 ( ) PDF全文 ( )

可视化

Spatial clustering behaviors in globally coupled rotator systems are explored, statistical properties of cluster and disordered states are analyzed, scaling relations between the averaged lifetime of the clustering states and the coupling parameter are obtained. It is pointed out that clustering behavior also exists in the weakly antiferromagnetic case. Clustering is also investigated in terms of averaged localization in tangent space, it is shown that localization in tangent space corresponds to broken ergodicity. Influence of local coupling is studied, it is found that there exists a best local coupling which possesses the longest lifetime.

Select

Perturbation Theory for Nonlinear Klein-Gordon Kinks

YAN JiaRen, TANG Yi, ZHOU GuangHui

理论物理通讯. 1999, 32(3): 375-380.

摘要 ( ) PDF全文 ( )

可视化

A direct approach is used to investigate perturbations about a kink solution for nonlinear Klein-Gordon models. Effects of perturbations on a kink are derived in this scheme. After linearizing the initial equations by making use of derivative expansion method from classical perturbation theory, the solution for the first-order correction is derived by means of the method of Laplace transformation. The parameter variations are naturally given by the secular conditions.

Select

On Torsion and Nieh-Yan Form

GUO HanYing, WU Ke, ZHANG Wei

理论物理通讯. 1999, 32(3): 381-386.

摘要 ( ) PDF全文 ( )

可视化

Using the well-known Chern-Weil formula and its generalization, we systematically construct the Chern-Simons forms and their generalization induced by torsion as well as the Nieh-Yan (N-Y) forms. We also give an argument on the vanishing of integration of N-Y form on any compact manifold without boundary. A systematic construction of N-Y forms in D = 4n dimensions is also given.

Select

Reduction of the Many-Body Problem and the Unified Theory for Nuclear Reaction

ZHANG QiRen

理论物理通讯. 1999, 32(3): 387-394.

摘要 ( ) PDF全文 ( )

可视化

We reduce the many-body problem to a multi-channel few-body problem by the AGS method. The channels may be chosen according to the problem under consideration and the reduction is formally exact. For the nuclear reaction we may choose some one-body channels to represent compound nucleus and choose some two- or more-body channels to represent open reaction channels. We then apply formal collision theory to this multi-channel system. Direct reaction, resonant reaction and their interference emerge. There are also distortions of ingoing and outgoing waves in compound nucleus formation and decay respectively. The omission of all but one open channel leads to the optical model, and an incomplete consideration of the open channels may lead to a multi-channel generalization of the optical model. Nonnucleon degrees of freedom as well as relativity may be included in principle. The reaction induced by particles other than nuclei may be considered on the same footing.

Select

Meson-Nucleon Scatterings in an SU(3) × SU(3) σ Model

ZHUANG PengFei

理论物理通讯. 1999, 32(3): 395-402.

摘要 ( ) PDF全文 ( )

可视化

Meson-nucleon scatterings are investigated in an SU(3) x SU(3) a model with scalar, vector, pseudoscalar and pseudovector couplings between mesons and baryons. from the calculation of effective coupling constants, sigma terms and s-wave scattering lengths for πN and K⁺N scatterings in the tree approximation, we find that the pseudoscalar coupling dominates s- and u-channel baryon Born terms, and the cancellation between the scalar and vector interactions leads to reasonable meson-nucleon scattering properties.

Select

Is There Really a Spin Crisis?

QING Di, CHEN XiangSong, SU WeiNing, WANG Fan

理论物理通讯. 1999, 32(3): 403-410.

摘要 ( ) PDF全文 ( )

可视化

The matrix element of quark axial vector current is shown to be different from the nonrelativistic quark spin sum for a nucleon at rest. The nucleon spin content discovered in polarized deep inelastic scattering is shown to be accommodated in a constituent quark model with 15% sea quark component mixing. The relativistic correction and sea quark pair excitation inherently related to quark axial vector current reduce the nucleon axial charge and this reduction is compensated by the relativistic quark orbital angular momentum exactly and in turn keeps the nucleon spin 1/2 untouched. Nucleon tensor charge has similar but smaller relativistic and sea quark pair excitation reduction.

Select

The Mass Gap of SU(2) Lattice Gauge Theory in 2+1 Dimensions

FANG XiYan, GUO ShuoHong, PAN ZhiGang

理论物理通讯. 1999, 32(3): 411-418.

摘要 ( ) PDF全文 ( )

可视化

Coupled cluster expansions are applied to study the eigenvalue problem of the Hamiltonian lattice gauge theory with the orthogonal D-loop basis being used to expand wavefunctions. The 0⁺⁺ bound state wavefunction and its mass gap relative to the vacuum of SU(2) lattice gauge theory in 2+1 dimensions are calculated up to the 7th order.

Select

On Possible Sources of Heavy Neutral Particles in Cosmic Rays

LI XueQian, REN xinGuo, TAO ZhiJian

理论物理通讯. 1999, 32(3): 419-424.

摘要 ( ) PDF全文 ( )

可视化

We explore some possible mechanisms by which the heavy neutral cosmic particles are accelerated to gain sufficiently high kinetic energies and cause observable effects at detectors on the earth. Our results indicate that all the known sources which are based on the established theories and observations fail to give rise to very high energy with sizable flux intensity. If the heavy neutral particles of kinetic energies of GeV order indeed exist in cosmic rays, there must be certain mechanisms beyond our present knowledge of dark matter and universe evolution.

Select

Top-Quark Condensate at Finite Temperature and Electroweak Symmetry Restoration

ZHOU BangRong

理论物理通讯. 1999, 32(3): 425-434.

摘要 ( ) PDF全文 ( )

可视化

The gap equation at finite temperature in the top-quark condensate scheme of electroweak symmetry breaking is proven to have the identical form in both the imaginary and real time formalisms of thermal field theory. By means of the gap equation, combined with the basic relation to define the vacuum expectation value v of the effective Higgs field, we analyze the dependence on temperature T and chemical potential p of the dynamical top-quark mass as the order parameter characteristic of symmetry breaking, and obtain the p-T criticality curve for symmetry restoration. We find out that the critical temperature T_c = 2υ for μ = 0 and the critical chemical potential μ_c = 2 π υ / √3 for T = 0. When μ = 0, the top-quark mass near T_c has the leading (T_c² - T²)^1/2 behavior with an extra factor dependent on temperature T and the momentum cutoff Λ. However, it is generally argued that the symmetry restoration at T ≥ T_c is still a second-order phase transition.

Select

Wavefunctions for Particles of Half-Integer Spins

ZHU JieJie, RUAN TuNan

理论物理通讯. 1999, 32(3): 435-442.

摘要 ( ) PDF全文 ( )

可视化

Explicit expressions of canonical and helicity wavefunctions for particles of halfinteger spins in two-component form and four-component form are derived. Properties of these wavefunctions are discussed in detail.

Select

Demonstration of the Double Q²-Rescaling Model

PENG HongAn, QIAO CongFeng, XU JiaSheng, HE ZhenMin

理论物理通讯. 1999, 32(3): 443-452.

摘要 ( ) PDF全文 ( )

可视化

In this paper we have demonstrated the double Q²-rescaling model (DQ²RM) of parton distribution functions of nucleon bounded in nucleus. For different χ regions in I-A deep inelastic scattering process we take different approaches: in high χ region (0.1 ≤ χ ≤ 0.7)we use the distorted QCD vacuum model which resulted from topologically multi-connected domain vacuum structure of nucleus; in low χ region (10^-4 ≤ χ ≤ 10^-3) we adopt the Glauber (Mueller) multi-scat tering formula for gluon coherently rescat tering in nucleus. From these two approaches we show that the rescaling parton distribution functions in bound nucleon are in good agreement with those we got from DQ²RM, thus the validity for this phenomenological model is demonstrated.

Select

Can a Nonextreme Kerr-Newman Black Hole Be Transformed into an Extreme One?

WANG Bin, SU RuKeng

理论物理通讯. 1999, 32(3): 453-456.

摘要 ( ) PDF全文 ( )

可视化

Extending the gedanken experiment suggested by Wald, Bekenstein and Rosenzweig, we have proved that a nonextreme Kerr-Newman black hole cannot become extreme by swallowing charged rotating test particles.

Select

Fermion-Fermion Stars

JIN KeJian, ZHANG YuanZhong

理论物理通讯. 1999, 32(3): 457-462.

摘要 ( ) PDF全文 ( )

可视化

The fermion-fermion stars, i.e., the dark matter self-gravitating systems made from two kinds of fermions with different masses, are considered. We review the stability of the systems, present a comparison between the maxima of gravitational redshift for fermion stars, compact stars, Bondi stars, bonson stars and fermion-fermion stars, and then investigate rotation curves of fermion-fermion stars (two-component concentric spheres) which might be polytropic dark matter halos of galaxies. Results show that the fermion-fermion stars would give rotation curves with flat part at large radii. This presents a striking contrast with the rotation curve of a single component fermion star which has no flat parts.

Select

Unified Approach for the Kerr Effect, Stark Effect and Doppler Effect in the Atom-Field Interaction

WANG XiaoGuang, YU RongJin

理论物理通讯. 1999, 32(3): 463-466.

摘要 ( ) PDF全文 ( )

可视化

We solve the atom-field interaction model including the Kerr effect, Stark effect and Doppler effect exactly within a unified approach. The detuning in the effective Hamiltonian depends on two conserved operators of the system. Finally, the influence of atomic mass center motion on the antibunching effect of photons is discussed.

Select

The MACQM Calculation of the Total Energy Curve for the Equilateral Triangle Structure of H₃⁺ Cluster

LI Ping, YIN Hual, GOU QingQuan, MIA0 JingWei

理论物理通讯. 1999, 32(3): 467-470.

摘要 ( ) PDF全文 ( )

可视化

Considering that the cluster H₃⁺ can be formed from the interaction of H⁺ with two hydrogen atoms, a modified arrangeLent channel quantum mechanics method has been used to calculate the total energy curve for the equilateral triangle structure of H₃⁺. The result shows that the curve has a minimal energy -1.2306 a.u. at the internuclear distance R = 1.97ao = 1.04 Å. This bond length is in good agreement with the experimental value of R = 0.98 ± 0.02 Å.

Select

Completeness Relation of Squeezed States in Squeezing Parametric Space Gained by Virtue of IWOP Technique

FAN HongYi, LIU NaiLe

理论物理通讯. 1999, 32(3): 471-474.

摘要 ( ) PDF全文 ( )

可视化

Using the newly developed technique of integration within an ordered product of operators, we prove that single-mode (or two-mode) squeezed states span a complete space in squeezing parametric space. The proof is concise and direct, and no further knowledge of SU(1,l) general coherent state theory is needed in our discussion.

Select

Common Shift Operators of {H, L²} for N-Dimensional Harmonic Oscillator

CHEN GuangZhou, LIU Yong, WANG XueHong, CHEN JingLing, GE MoLin

理论物理通讯. 1999, 32(3): 475-476.

摘要 ( ) PDF全文 ( )

可视化

The common shift operators of {H, L²} for N-dimensional harmonic oscillator are established.

Select

Supersymmetric Quantum Mechanics in d-Dimensional Space

RUAN Dong, TU ChangCun, SUN HongZhou

理论物理通讯. 1999, 32(3): 477-480.

摘要 ( ) PDF全文 ( )

可视化

Two different forms of d-dimensional supersymmetric quantum mechanics are constructed from 1-dimensional one by means of two complex Clifford algebras C(d, 0) and C(0, d) respectively. The two new d-dimensional realizations are based upon the more general supercharges, which include not only a vector superpotential but also a complex scalar superpotential, and bring out the richer structures.

选择文件类型/文献管理软件名称

选择包含的内容

1999年, 第32卷, 第3期　
刊出日期：1999-10-30

模态框（Modal）标题

选择文件类型/文献管理软件名称

选择包含的内容

1999年, 第32卷, 第3期 刊出日期：1999-10-30

1999年, 第32卷, 第3期　
刊出日期：1999-10-30