Equilibrium dynamics of the sub-Ohmic spin-boson model under bias

Using the bosonic numerical renormalization group method, we studied the equilibrium dynamical correlation function C(ω) of the spin operator σ_z for the biased sub-Ohmic spin-boson model. The small-ω behavior C(ω) ∝ω~s is found to be universal and independent of the bias ε and the coupling strength α(except at the quantum critical point α = αc and ε = 0). Our NRG data also show C(ω) ∝χ~2ω~s for a wide range of parameters, including the biased strong coupling regime(ε = 0 and α α_c), supporting the general validity of the Shiba relation. Close to the quantum critical point αc,the dependence of C(ω) on α and ε is understood in terms of the competition between ε and the crossover energy scale ω_0~*of the unbiased case. C(ω) is stable with respect to ε for ε《ε~*. For ε》ε~*, it is suppressed by ε in the low frequency regime. We establish that ε~*∝(ω_0~*)~(1/θ)holds for all sub-Ohmic regime 0≤s 1, with θ = 2/(3s) for 0 s≤1/2 and θ = 2/(1 + s) for 1/2 s 1. The variation of C(ω) with α and ε is summarized into a crossover phase diagram on the α–ε plane.     

KM Matrix Parametrizatidn Convenient for Both Bd Study and Data Analysis

The value of the ε parameter of a pseudoscalar mixing system is phase-conventiondependent. We prove that one can make two of the three ε parameters, ε_K, ε_Bd and ε_Bd, small but not all of them simultaneously by adjusting the phase convention of the Kobayashi-Maskawa (KM) matrix. We give corresponding KM matrices based on the Wolfenstein parametrization, which are also suitable for ahalyzing the values of KM parameters. The transformation from one matrix to the other is extremely simple.     

Short-Time Dynamics of the Random n-Vector Model

Short-time critical behavior of the random n-vector model is studied by the theoretic renormalization-group approach.Asymptotic scaling laws are studied in a frame of the expansion in ε = 4 - d for n ≠ 1 and √ε for n = 1respectively.In d ＜ 4,the initial slip exponents θ′ for the order parameter and θ for the response function are calculated up to the second order in ε ＝ 4 - d for n ≠ 1 and √ε for n ＝ 1 at the random fixed point respectively.Our results show that the random impurities exert a strong influence on the short-time dynamics for d ＜ 4 and n ＜ n_c.     

The Convection Instability of Bhnard-Rayleigh Fluid Under Varied External Force

A new model of Bknard-Rayleigh convection has been put forward from mantle convection and liquid crystal, where the external force deviates from constant to a lineal function of vertical dimension z. The dimensionless parameter ε is induced to describe the scale of this kind of deviations. Through linear stability analyses, we find that even-odd symmetry broken appears. By numerical calculation under rigid boundary conditions, we find that α_c is almost α constant but R_c decreases nonlinearly as ε increases, so the increase of ε benefits convection. When ε=0, all results reduce to the former works automatically.     

Nonlinear Response of Granular Composite Mediurn

In this paper, the linear and nonlinear responses of granular composite medium consisting of spherical grains with coating shells embedded in a host medium are studied. We assume that the shell and the host medium are linear (the dielectric constants of which are ε⁰ and ε_m⁰ respectively), while the spherical grain is nonlinear (the diektric constant of which is ε_c = ε_c⁰ + χ_c|E_c|^β). Starting from the definition (D) = ε_eff and taking in to account the corrections to the local field within the spherical grains, expressions for the linear and high-order nonlinear susceptibilities are presented.     

Soliton Excitations in the Compressible Heisenberg Spin Chain: A General Approach

A general approach is given for the nonlinear excitations in the compressible Heisenberg ferromagnetic chain in coherent-state representation. It is shown that the relative ratio of ε to δ is very important for determining the nonlinear modified terms of the equations of motion. ε = 1√S (S is the spin length) and δ = α/λ₀ (α is the lattice constant and λ₀ is the characteristic wavelength of the excitations) are two small dimensionless parameters used in the semiclassical approximation and in the long wavelength approximation, respectively. In the case of δ = O(ε), the reduced equations of motion are solved exactly and spin soliton and elastic kink solutions are obtained. The other cases of the relation between δ and ε are also discussed and the solitary wave solutions are also given. The result obtained by Ferrer, as a special case, has been included in our approach.     

HL-1M装置逃逸电子的定标律

使用一维数值模型, 推断了逃逸能量ε_r与逃逸约束时间τ_r的关系。模拟结果给出能量ε_r 和放电参数的定标律。在HL- 1M 装置中不同实验条件下测量了硬X 射线谱, 研究了逃逸电子能量 ε_r模拟的定标律, 并推导出HL- 1M 装置放电的逃逸电子的约束时间与逃逸电子扩散系数。     

Alternating-current relaxation of a rotating metallic particle

Based on a first-principles approach,we establish an alternating-current(AC) relaxation theory for a rotating metallic particle with complex dielectric constant ε_α=ε_α-iσ_α/ω_0.Here εα is the real part,σ_α the conductivity,ω_0 the angular frequency of an AC electric field,and i=-1~(1/2).Our theory yields an accurate interparticle force,which is in good agreement with the existing experiment.The agreement helps to show that the relaxations of two kinds of charges,namely,surface polarized charges(described by ε_α) and free charges(corresponding to σ_α),contribute to the unusually large reduction in the attracting interparticle force.This theory can be adopted to determine the relaxation time of dynamic particles in various fields.     

各向异性表面张力对定向凝固中共晶生长形态稳定性的影响

研究各向异性表面张力对定向凝固中共晶生长形态稳定性的影响.应用多重变量展开法导出了共晶界面表达式和扰动振幅的变化率满足的色散关系.结果表明,共晶生长系统有两种整体不稳定性机理:由非震荡导致的"交换稳定性"机理和由震荡导致的"整体波动不稳定性"机理.震荡有四种典型模式,即:反对称-反对称(AA-),对称-反对称(SA-)、反对称-对称(AS-)和对称-对称(SS-)模式.稳定性分析表明:共晶界面形态稳定性取决于Peclet数ε的某一个临界值ε_*,当ε大于临界值ε_*时,共晶界面形态不稳定;当ε小于临界值ε_*时,共晶界面形态稳定.随着各向异性表面张力增大,对应于AA-,SA-和SS-模式的临界值ε_(aa*),ε_(sa*)和ε_(ss*)随之减小,表明各向异性表面张力减小这三种模式的稳定性区域;然而,随着各向异性表面张力增大,对应于AS-模式的临界值ε_(as*)随之增大,表明各向异性表面张力增大AS-模式的稳定性区域.     

The Effective Hamiltonian for Nonleptonic Decay with Possible mt >mw and the ΔI=1/2 Rule1

The effective Hamiltonian for nonleptonic decays of strange, charm and beauty, involving the QCD corrections at short distances but with possible t-quark mass m_t > mw and a correction of the initial value for the renormalization group equations, is computed in the framework of the operator product expansion (OPE). The numerical results show that our calculation gives corrections in right direction for approaching to the Δ1=1/2 rule and if using the latest experimental measurements on δ and ε'/ε for system as input, the KM parameter ε₂² would be constrained in a reasonable region (2.5～22.5)×10^-3.     

煤层底板突水监测预警光纤应变传感器的研制

针对煤层底板突水监测预警系统对应变传感器的特殊要求,研制了新型光纤光栅三分量应变传感器。三分量应变传感器采用内置温度补偿芯片的温度补偿方法,通过将3个应力芯片按一定角度放置的封装工艺研制而成。对所研制的光纤光栅应变传感器进行了温度特性试验、系统基本性能指标试验、疲劳耐久性试验等,试验结果表明:所研制的传感器在使用温度0℃～40℃内,灵敏系数为1.23 pm/,应变量程为1 000 ;横向效应为0.39%,机械滞后为1.18 ,蠕变为1.53 ,线性度为0.13%,重复性为0.16%,工作性能满足设计要求。经过煤层底板突水监测工程实例,验证了新型光纤光栅应变传感器均能准确感应煤层底板应变信息,可对监测点80 m范围内进行预警。     

Semi-Relativistic Reflection and Transmission Coefficients for Two Spinless Particles Separated by a Rectangular-Shaped Potential Barrier

A generalized Schrödinger approximation, due to Ikhdair & Sever, of the semi-relativistic two-body problem with a rectangular barrier in (1+1) dimensions is compared with exact computations. Exact and approximate transmission and reflection coefficients are obtained in terms of local wave numbers. The approximate transmission and reflection coefficients turn out to be surprisingly accurate in an energy range |ε-V₀|<2μ c², where μ is the reduced mass, ε the scattering energy, and V₀ the barrier top energy. The approximate wave numbers are less accurate.     

Soliton-Like Bi-plasma Polaron

In the framework of phonon-plasmon cooperative effect mechanism, the differential equation for the wavefunction of the travelling soliton-like bi-plasma polaron (BPP) is derived. Then it is proven that the solution can be simply one-dimensional form. Meanwhile, the velocity range of the travelling soliton-like BPP is studied, thereby, we found that the quantity η=ε_∞/ε₀ of the materials, where the travelling soliton-like BPP can exist, should be very small, i.e. η→0. This result is consistent with the recently reported ones. Finally, an analytic approximation solution is given.     

Replicon Modes in the Renormalization Group with Replica Symmetry Breaking

Abstract The renormalization group with replica symmetry (RSB) breaking is studied for the disordered ferromagnets. The ε-expansion (ε= 4-D, D is the spatial dimension) is used. For fixed points with step-like RSB structufe replicon eigqnvalpes are defined to describe the stability of the fixed points with respect to the continuous lESB perturbation.It is shown that this metliod can be generalized to the cases in which the number of the steps in the step-like RSB structure ahd the order of expansion are arbitrary.     

非简谐振动对石墨烯杨氏模量与声子频率的影响

在哈里森键联轨道法框架下, 考虑到原子的短程相互作用和原子的非简谐振动, 应用固体物理理论和方法, 得到了石墨烯的力常数、杨氏模量、扭曲模量、泊松系数以及声子频率随温度的变化关系, 探讨了非简谐振动对它们的影响. 结果表明: 1)杨氏模量与声子频率等随温度变化并遵从一定的规律, 其中力常数、杨氏模量、扭曲模量随温度升高而增大, 但变化较小; 声子频率随温度升高而增大但变化较快; 泊松系数随温度升高而较快地减小; 2)石墨烯原子具有沿键长方向的纵振动和垂直键长方向的横振动, 但以纵振动为主, 纵振动的非简谐效应远大于横振动, 横振动的简谐系数ε₀' 和第二非谐系数ε₂' 均小于纵振动的相应值ε₀,ε₂; 比值为ε₀/ε₀' ≈ 8.477,ε₂/ε₂' ≈ 156; 3)若不考虑非简谐振动项, 则石墨烯的力常数、杨氏模量和扭曲模量、泊松系数、声子频率均为常量, 与实验不符合; 同时考虑到原子的第一、二非简谐振动项后, 它们均随温度升高而变化, 而且温度愈高, 原子振动的非简谐效应愈显著. 本文的结果与文献的实验结果符合较好.     

核磁共振的差谱在天然产物研究中的应用（Ⅰ）

提出应用核磁共振差谱研究天然产物混合物的方法. 在对黄海繁茂膜海绵天然产物的研究中，通过柱分离的溶剂强度连续变化，获得连续洗脱物，对这几个连续洗脱物的核磁共振谱图进行比较得出差谱，实现核磁共振谱峰的分类、归属，从而解析出各个化合物. 在此过程中也可以获得被分离物与溶剂强度之间的关系.     

A Hierarchy of Universal Quantities in RG Equations for the 2D Coulomb Gas

A hierarchy of universal quantities in the double expansion RG equations for two dimensional (2D) Coulomb gas is found by using a length-dependent dielectric function ε(γ).     

Equation of State of the Strong Interaction Matter in an External Magnetic Field

We investigate the equation of state of the strong interaction matter in a background magnetic field via the two flavor Nambu-Jona-Lasinio model. Starting from the mean-field thermodynamical potential density Ω, we calculate the pressure density p, the entropy density s, the energy density ε, and the interaction measure (ε-3p)=T⁴ of the strong interaction matter at finite temperature and finite magnetic field. The results manifest that the chiral phase transition is just a crossover but not a low order phase transition. Moreover there may exist magnetic catalysis effect, and its mechanism is just the effective dimension reduction induced by the magnetic field.     

Dielectric loss of half-doped manganite La_(0.5)Ca_(0.5)MnO_3

The dielectric loss tanδ of half-doped manganite La 0.5 Ca 0.5 MnO 3 is investigated using Green's function technique. The La 0.5 Ca 0.5 MnO 3 is described by the Kondo-lattice model in the double exchange limit, taking into account the Jahn-Teller distortion and the super-exchange interaction between the localized electrons. It is found that the intensity of tanδ decreases with increasing | ε JT |, V, and U. It is also observed that the transition temperature T P rises as | ε JT | and U increase. It is worth noting that T P remains unchanged and the strength of tanδ increases with increasing g. The calculated dielectric loss results are explained theoretically, and these behaviors are in qualitative agreement with the experimental results.     

Conformal Invariance and the Lanczos Method Studies of Ashkin-Teller Quantum chain

The low-lying energy spectrum of quantum Ashkin-Teller chain in the critical region is calculated by using Lanczos method. According to conformal theory, the scaling dimensions Χ and the normalizing factor ε are obtained from the energy spectrum.