自旋场对Barriola-vilenkin黑洞熵的量子修正

用砖墙模型的方法，讨论了无源引力场对Barriola-Vilenkin黑洞熵的量子修正.计算表明， 量子修正应该包含两部分：其中一部分与视界面积成正比，在视界附近与紫外截断因子是 平方反比发散的；另一部分是两个对数发散项，这部分除了与黑洞的本身特征性质(M，η) 有关以外，还与自旋场的自旋有关.结果与标量场引起的量子修正具有完全不同的形式. 关键词： 砖墙模型 量子修正 黑洞熵     

Quantum corrections to the energy density of a homogeneous Bose gas

Quantum corrections to the properties of a homogeneous interacting Bose gas at zero temperature can be calculated as a low-density expansion in powers of , where is the number density and a is the S-wave scattering length. We calculate the ground state energy density to second order in . The coefficient of the correction has a logarithmic term that was calculated in 1959. We present the first calculation of the constant under the logarithm. The constant depends not only on a, but also on an extra parameter that describes the low energy scattering of the bosons. In the case of alkali atoms, we argue that the second order quantum correction is dominated by the logarithmic term, where the argument of the logarithm is ,and is the length scale set by the van der Waals potential. Received 2 February 1999     

Trace formula for level density of a spherical billiard

A trace formula for the oscillating part of the level density for a spherical billiard has been obtained in spherical polar coordinates. The Jacobian of stability and the length of the orbits are obtained from the classical mechanics of the problem. The same formula is applicable to both the planar and the diametric orbits. Numerical results have been obtained with this formula and compared with the results from exact quantum theory, EBK quantization, and Balian and Bloch.     

Effect of laser radiation on optical properties of disk shaped quantum dot in magnetic fields

The optical absorption coefficients and changes in the refractive index in GaAs/AlGaAs, disk shaped quantum dots (DSQD) with simultaneously applied laser and magnetic field are studied in detail. The use of the density matrix formalism is made to study the variations in linear and non-linear polarizability with the frequency of the electric field. It is found that the absorption coefficient and the refractive index changes depend not only on the optical wave but also on the strength of the static magnetic field.     

Quantum corrections to the semiclassical Hartree-Fock theory of a harmonically trapped Bose gas

An analytical approach is proposed to investigate the mechanism of implantation of size selected clusters into graphite, in order to explain the origin of linear variation of measured penetration depth with momentum or energy of incident cluster. In agreement with experimental observations, the cluster experiences, during its penetration, a force which consists in a component proportional with cluster velocity and a constant component. Expressions of these forces were obtained in the frame work of this approach. Regardless of whether the cluster breaks down into single atoms on the surface or not, there is evidence for existence of a wave generated under impact of cluster on the surface. Under the assumption that the cluster does not break up at impact on the surface, the penetration depth depends on the cross-section between the cluster and the surface, the cluster velocity and the properties of graphite. When the cluster fragments upon the impact on the surface, the generated wave is followed by a collective motion (??collective cascade??) of displaced atoms of target, including the constituents of cluster themselves, due to the transfer of cluster momentum. Thus, it is these displaced atoms which penetrate in the medium. During this collective penetration, some constituents of cluster can reach a certain depth which may be considered as the range of the deepest implanted constituents of cluster. It is shown that, the depth of penetration depends on the initial radius of cluster, its velocity and the properties of graphite. In addition, the depth varies non linearly with cluster velocity, for small clusters (n ?? 7), while for large clusters (n ?? 13), it varies (i) linearly with cluster velocity (or momentum) when the force proportional with speed of cluster is dominant. (ii) Linearly with the square of cluster velocity (or energy) if the constant force becomes dominant. It is shown that, a mechanism based on a collective motion of displaced atoms including the constituents of cluster themselves, induced by transfer of cluster momentum to the medium, permits to explain the behavior of measured depth of implanted clusters into graphite. This collective motion involves only one free parameter for all clusters of the same nature which are used as projectiles in the same experiment.     

本征约瑟夫森结跳变电流分布的量子修正

在约瑟夫森结跳变电流统计分布的理论拟合过程中,通常考虑的是宏观量子隧穿与热激活这两种过程. 对Bi₂Sr₂CaCu₂O_8+δ表面本征约瑟夫森结的结果分析表明,在宏观量子隧穿与热激活的交界区域内,若考虑量子修正能使实验曲线与理论曲线符合得更好. 这种较为完整的拟合方法,对研究本征约瑟夫森器件中的宏观量子现象及其在超导量子比特中的应用具有积极的意义. 关键词： 约瑟夫森结 跳变电流分布 量子修正     

Quantum corrections to the thermodynamic properties of a two-dimensional fluid with hard-core potential

A simple theory, based on the physical interpretation of the reciprocal of activity, is developed to evaluate the thermodynamic properties of a two-dimensional fluid in the semi-classical limit. The theory is applied to calculate the quantum corrections to the equation of state and excess free energy of two-dimensional fluids, whose molecules interactvia hard-disc and square-well potential. It is found that the quantum effect increases with the increase of density and decrease of temperature.     

Quantum corrections to thermodynamics of polar hard sphere fluids

The quantum corrections to the thermodynamic properties of polar hard sphere fluids and fluid mixtures are estimated taking into account the influence of dipole and quadrupole moments. Expressions are given for the second virial coefficient, free energy and pressure and results are given for different values ofμ* andϑ*. The first order quantum correction arises due to the translational contribution only. The quantum effect increases with density,μ* andϑ*. Numerical results are also estimated for binary mixtures of (i) hard spheres and dipole hard spheres and (ii) hard spheres and quadrupole hard spheres. The ‘excess’ free energy for dipole hard sphere binary mixture is also reported. It is found that the ‘excess’ quantum effect depends on the concentration and the particle diameter ratio and increases with increase ofμ* andϑ*.     

类铝离子基态能量的相对论修正和Z相关修正

以Breit-Pauli哈密顿的球张量形式为基础,借助不可约张量理论,在拉卡表象下计算了类铝体系基态能量相对论修正(包括相对论质量修正项、单体和双体达尔文修正项、自旋-自旋接触和轨道-轨道相互作用项)。在此基础上,引入了一个与核电荷数Z相关的能量修正项,用以弥补因忽略能量的其它高阶项对原子体系能量的影响。计算结果与实验值非常接近。     

多电子原子能量的相对论修正

以Breit-Pauli哈密顿的球张量形式为基础,借助不可约张量理论,建立了计算多电子原子能量的相对论修正的一种解析理论形式,导出了多电子原子相对论修正项(包括相对论质量修正项、单体和双体达尔文修正项、自旋-自旋接触相互作用项和轨道-轨道相互作用项)在斯莱特表象中的矩阵元的解析表达式,完成了所有角向积分和自旋求和计算.利用所建立的理论,对类锂体系(1s)2(2p)2P态能量的相对论修正进行了具体计算.     

Quantum corrections to the conductance of n-GaAs films in a strong magnetic field

The conductance of doped n-GaAs films is studied experimentally as a function of magnetic field and temperature in strong magnetic fields right up to the quantum limit (ħω_c = E _F). The Hall conductance G _xy is virtually independent of temperature T until the transverse conductance G _xx is quite large compared with e ²/h. In strong fields, when G _xx becomes comparable to e ²/h, G _xy starts to depend on T. The difference between the conductances G _xx at the two temperatures 4.2 and 0.35 K depends only weakly on the magnetic field H over a wide range of magnetic fields, while the conductances G _xx themselves vary strongly. The results can be explained by quantum corrections to the conductance as a result of the electron-electron interaction in the diffusion channel. The possibility of quantization of the Hall conductance as a result of the electron-electron interaction is discussed. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 3, 201–206 (10 February 1998)     

原子核体积和质量效应对较轻元素及同位素类氢离子能级的修正

在类氢离子电子束缚能一级相对论修正的基础上,计算了原子核的体积效应及质量效应对较轻元素及同位素类氢离子能级的修正量,结果显示,原子核的体积及质量效应不仅导致同位异核氢及类氢离子精细结构能级出现分裂,还会导致类氢离子精细结构能级的简并消失。     

QCD and electro-weak corrections to the production of Higgs+2 jets at the LHC

We present complete next-to-leading-order (NLO) QCD correction and electro-weak (EW) correction to the production cross section of Higgs-Boson in association with two hard quark jets by using Monte-Carlo numerical calculation program, HAWK, for various photon parton distribution functions at the Large Hadron Collider with center of mass energy 7, 8, 13, and 14 TeV without and with typical vector-Boson-fusion cuts on the tagging jets. In our calculation we include complete contribution from the full set of t-channel, u-channel and s-channel Feynman diagrams, and corresponding interferences as well as NLO QCD and EW corrections.     

Quantum gravity stability of isotropy in homogeneous cosmology

It has been shown that anisotropy of homogeneous spacetime described by the general Kasner metric can be damped by quantum fluctuations coming from perturbative quantum gravity in one-loop approximation. Also, a formal argument, not limited to one-loop approximation, is put forward in favor of stability of isotropy in the exactly isotropic case.     

Considerations concerning the radiative corrections to muon decay in the Fermi and Standard theories

The FAC, PMS, and BLM optimization methods are applied to the QED corrections to the muon lifetime in the Fermi V-A theory. The FAC and PMS scales are close to m_e, while the BLM scale nearly coincides with the geometric average √m_em_μ. The optimized expressions are employed to estimate the third order coefficient in the (m_μ) expansion and the theoretical error of the perturbative series. Using arguments based on effective field theory and a simple examination of Feynman diagrams, it is shown that, if contributions of (m_μ²/M_W²) are neglected, the corrections to muon decay in the SM factorize into the QED correction of the Fermi V-A theory and the electroweak amplitude g²/(1 − Δr), both of which are strictly scale-independent. We use the results to clarify how the QED corrections to muon decay and the Fermi constant G_F should be used in the SM, and what is the natural choice of scales if running couplings are employed.     

氩原子和类氩离子相对论修正

以相对论修正哈密顿(包括质量修正、单体和双体达尔文修正、自旋-自旋接触相互作用)的球张量形式为基础, 借助不可约张量理论导出了类氩体系基态能量的相对论修正的解析表达式. 在斯莱特表象中完成了所有的角向积分和自旋求和计算, 能量的相对论修正式用径向矩阵元的线性组合来表示.对类氩体系基态能量的相对论修正值进行了具体计算,相对误差均小于0.0459%     

Quark mass corrections to the perturbative thrust and its effect on the determination of αs

We consider the effects of quark masses to the perturbative thrust in e ⁺ e ⁻ annihilation. In particular we show that perturbative power corrections resulting from non-zero quark masses considerably alters the size of the non-perturbative power corrections and consequently, significantly changes the fitted value of α_s.     

平行电磁场中锂原子自电离的半经典分析

采用包含组合回归的扩展的闭合轨道理论计算了平行电磁场中锂原子依赖于时间的自电离谱,并用半经典的方法解释了电离过程中的混沌现象.讨论了电离电子逃逸时间谱分形结构中隐含的各韵律段的电离轨迹,并得到了轨迹的一般规律,其中特别关注由核散射产生的特殊的逃逸轨迹的性质.具体研究了磁场对锂原子自电离混沌脉冲阵列中电子逃逸轨道和逃逸时间谱的影响.结果发现随着外加磁场的增大,电离脉冲越来越复杂,混沌现象也越明显.这显示了逃逸轨道对初始条件的敏感依赖性.     

The quantum spectra analysis of the circular billiards in wells

We use a recently defined quantum spectral function and apply the method of closed-orbit theory to the 2D circular billiard system. The quantum spectra contain rich information of all classical orbits connecting two arbitrary points in the well. We study the correspondence between quantum spectra and classical orbits in the circular, 1/2 circular and 1/4 circular wells using the analytic and numerical methods. We find that the peak positions in the Fourier-transformed quantum spectra match accurately with the lengths of the classical orbits. These examples show evidently that semi-classical method provides a bridge between quantum and classical mechanics.     

On the corrections to scaling in three-dimensional Ising models

The leading correction-to-scaling amplitudes for the spin-1/2, nearest-neighbor sc, bcc, and fee Ising models are considered with the particular aim of determining their signs. On the basis of previous two-variable series analyses by Chen, Fisher, and Nickel and renormalization group=4–d expansions, it is concluded that the correction amplitudes for the susceptibility, correlation length, specific heat, and spontaneous magnetization arenegative for all three lattices. Thus, for example, the effective exponent _eff(T) asymptotically approaches the true susceptibility exponent fromabove. Other earlier and more recent high-temperature series and field-theoretic analyses are seen to be consistent with this result. However, the usual nonasymptotic, perturbative field-theoretic approaches are essentially committed to positive correction amplitudes. The question of the signs therefore relates directly to the applicability of these non-asymptotic field-theoretic calculations to three-dimensional Ising models as well as to different experimental systems.