Semileptonic decays Bc→(ηc,J/Ψ)lv in the perturbative QCD approach

In this paper we study the semileptonic decays of B_c^-→(η_c,J/Ψ)l^-v_l. We first evaluate the B_c→(η_c,J/Ψ) transition form factors F₀(q²), F₊(q²), V(q²) and A_0,1,2(q²) by employing the pQCD factorization approach, and then we calculate the branching ratios for all considered semileptonic decays. Based on the numerical results and the phenomenological analysis, we find that: (a) the pQCD predictions for the values of the B_c→η_c and B_c→J/Ψ transition form factors agree well with those obtained by using other methods; (b) the pQCD predictions for the branching ratios of the considered decays are Br(B_c^-→η_c e^-v_e(μ^-v_μ)=(4.41_-1.09^+1.22)×10^-3, Br(B_c^-→η_cτ^-v_τ) =(1.37_-0.34^+0.37)×10^-3, Br(B_c^-→J/Ψ e^-v_e(μ^-v_μ)) =(10.03_-1.18^+1.33)×10^-3, and Br(B_c^-→J/Ψτ^-v_τ) =(2.92_-0.34^+0.40)×10^-3; and (c) we also define and calculate two ratios of the branching ratios R_ηc and R_J/Ψ, which will be tested by LHCb and the forthcoming Super-B experiments.     

高压下Gd3Ga5O12晶体的弹性性能

 利用超声“脉冲回波重合法”技术,测定了立方晶体镱镓石榴石（GGG）各对称方向的超声波声速,及它们在流体静压力和单轴应力条件下,随压力的变化,计算了GGG的二阶和三阶弹性常数。它们分别是：c₁₁=3.04,c₁₂=1.31,c₄₄=0.94和c₁₁₁=-17.97,c₁₁₂=-12.86,c₁₂₃=-1.06,c₁₄₄=-2.11,c₁₆₆=-3.29,c₄₅₆=-0.94,单位是10¹¹ N/m²。根据这些数据,我们还计算了GGG晶体的德拜温度以及沿它的[001]→[111]→[110]→[100]传播的三个声学波分支（一个纵波,两个横波）的Gruneisen参数γ(p,N)的分布。     

SU(2)×U(1)×S3模型及类K0-K0系统的混合和CP破坏效应

本文内容包括:(ⅰ)进一步给出SU(2)×U(1)×S₃模型的结果S₂≈S₃≈(m_s²)/(m_b²);sin δ≤(m_um_d)/(m_cm_s),并预言b夸克的主要衰变道是b→u+W,b夸克的寿命可能长到10^-9秒.(ⅱ)给出类K⁰-K⁰系统混合时的精确表达式ρ=错号事例数/对号事例数=(1/2)(|p/q|²+|q/p|²)([Γ²+(Δm)²]²-(γ1γ2)²)/([Γ²+(Δm)²]²+(γ1γ2)²);并给出CP破坏的精确表达式:A=(1-ρ')/(1+ρ')=(I_M12Γ₁₂^*)/(|M₁₂|²+1/4|Γ₁₂|²),这里ρ′=(负电错号事例数)/(正电错号事例数)。     

碱卤晶体热导率与压强的关系

 本文指出，关于碱卤晶体热导率λ与压强p之间关系的经验方程：λ=A+Bp或λ=A+Bp+Cp²，可以由Bridgman参量的定义g=-(d lnλ/dlnV)_T和Tait方程ΔV/V₀=ln(1+βp)/α导出。     

Bipartite entanglement in spin-1/2 Heisenberg model

The bipartite entanglement of the two- and three-spin Heisenberg model was investigated by using the concept of negativity. It is found that for the ground-state entanglement of the two-spin model, the negativity always decreases as B increases if Δ<γ－1, and it may keep a steady value of 0.5 in the region of B2－γ²]^1/2 if Δ>γ－1, while for that of the three-spin model, the negativity exhibits square wave structures if γ=0 or Δ=0. For thermal states, there are two areas showing entanglement, namely, the main region and the sub-region. The main region exists only when Δ>Δ_c (Δ_c=γ－1 and (γ²－1)/2 for the 2- and 3-spin model respectively) and extends in terms of B and T as Δ increases, while the sub-region survives only when γ≠0 and shrinks in terms of B and T as Δ increases.     

对爱因斯坦模型的修正及考虑热效应的三个通用状态方程

 对固体考虑热效应的爱因斯坦模型进行了修正。指出考虑热效应的通用状态方程中不应该包含零点振动项，方程参数不应该直接取为参考温度下的实验值V_R，B_R，B′_R和γ^G_R，而应该取为零温下的数值V₀，B₀，B′₀和γ^G₀；提出了一种从V_R，B_R，B′_R和γ^G_R求解V₀，B₀，B′₀和γ^G₀的方法。将提出的方法应用于三个典型的通用状态方程，包括Baonza、mMNH和Vinet方程。数值结果表明，利用相同的实验参数对三个方程解出的参数，以及预测的零压和低压下的热物理性质差异很小，而且都与实验数据符合很好。这些结果表明，在零压和低压下预测热物理性质的精确度不足以用来判断各种通用状态方程的适用性。     

A result on certain coset subalgebras of the βγ-system

In this paper, for the highest weight module V₄ of sl(2,C) with the highest weight 4, we describe subalgebras S_β(V₄)^θ+ and S_γ(V₄)^θ+ of the βγ-system coset S(V₄)^θ+ by giving their generators. These coset subalgebras are interesting, new examples of strongly finitely generated vertex algebra.     

非弹性散射中的四极-八极双声子激发

本文用DWBA方法对两种入射能量E_α=31和和43MeV的⁶⁴Zn(α, α′)⁶⁴Zn*非弹性散射中可能的四极-八极双声子激发进行了研究. 考虑了核力势和库仑势, 零级近似核力势取为Woods-Saxon势, 由靶核振动引起的核力势的非球对称部分V₁作为微扰. 在计算中, V₁取到核表面集体坐标α_λν的二级项, 总初态波函数Ψ⁽⁺⁾_i取到V₁的一级项,目在扭曲波格林函数中略去了作为中间态的吸收道. 此外在双声子激发机制中, 假设直接双声子激发的贡献是主要的, 相继双声子激发的贡献是次要的. 所得的理论角分布与实验符合得相当好. 由这样符合可推知⁶⁴Zn的3.72和4.19MeV能级是四极-八极双声子激发能级, 其角动量和宇称分别为3^－和5^－.     

高温超导体低温、高压下的物理性质的研究

 在3~20 GPa压力范围内，测量了含氧量较低的YBa₂Cu₃O_7-δ（δ=0.46）单晶压力增强效应（dT_c/dp=4.9KGPa^-1）；YBa₂Cu₃O₇（T_c0=90 K）单晶在压力下临界电流密度随压力变化；外磁场H=30 kO_e时，T_c与磁场、压力关系；压力达16.5 GPa下，Bi₂Sr₂CaCu₂O_x单晶T_c(p)关系（dT_c/dp=-0.4 KGPa^-1）。发现Y系高温超导体的温度压力导数dT_c/dp与T_c0中间呈dT_c/dp=b-mT_c0线性关系（b、m为常数）。结合压力下Y系超导体结构相变和含氧量对T_c影响，分析这类超导体T_c有很强的正压力效应的原因。把实验结果同几种超导电性微观理论模型进行了分析和比较。     

Synchrotron X-ray diffraction study of phenacite at high pressure

We report the results of a natural phenacite from 0 to 30.9 GPa using in situ angle-dispersive X-ray diffraction and a diamond anvil cell at the National Synchrotron Light Source, Brookhaven National Laboratory. Over this pressure range, no phase change or disproportionation has been observed. The isothermal equation of state was determined. The values of V₀, K₀, and K₀′ refined with a third-order Birch-Murnaghan equation of state are V₀=1116.1±1.2 ų, K₀=223±9 GPa, and K₀′=5.5±0.8. Furthermore, we confirm that the linear compressibilities (β) along a and c directions of phenacite are elastically isotropic (β_a=1.50×10^-3 and β_c=1.34×10^-3 GPa^-1). Consequently, it can be concluded that the compressibility of phenacite under high pressures has been accurately constrained.     

JB-9001钝感炸药冲击Hugoniot关系测试

 利用“压力对比法”实验技术，通过锰铜压力计测试待测炸药样品和LY12铝样品在LY12铝飞片的同时撞击下的界面压力p_exp和p_Al，从冲击波关系式和正交回归直线拟合分析，确定了JB-9001钝感炸药的冲击Hugoniot关系。     

Dependence of functional properties on processing in sol-gel (Pb,La)TiO3 thin films

Pb_0.88La_0.08TiO₃ films were processed on Si-based substrates by a diol-based sol-gel route from solutions with variable content of PbO excess. Crystallisation was performed at heating rates of 10 °C min^-1 and higher than 500 °C min^-1 (rapid heating). The pyroelectric coefficient was measured after poling the samples by two methods: applying a sinusoidal wave and applying a train of square pulses, with the latter showing a higher poling efficiency. The piezoelectric d₃₃ coefficient was determined by double-beam interferometry. Strain vs. field measurements provided evidence of 90° domain orientation in these films. Those crystallised at 10 °C min^-1 showed the highest functional properties (%=1.7᎒^-2 7C cm^-2 K^-1 and d₃₃=57 pm V^-1). This is a consequence of the higher stability of the 90° domains oriented during poling, caused by the lower tensile stress arising during preparation. The voltage responsivity of these films also benefited from the lower permittivity arising from their higher porosity. These films are good candidates for applications in infrared detectors and microelectromechanical devices.     

液态金属的定容比热随温度变化的理论研究

 Grover根据实验数据给出，液态金属的定容比热随温度近似线性减小：c_V≈3R-ζRT/T_m，式中T为温度，T_m为熔化温度，R为普适气体常数，ζ为经验常数，其值在0.11至0.24之间，就平均来说，ζ≈0.15。利用Lennard-Jones-Devonshire理论对这一经验关系进行了解释。     

氧化镍（绿镍矿）等温压缩及高压相变研究

 本文采用DAC（金刚石压砧高压腔）装置，对氧化镍进行了静水压、非静水压、电导率测量等系统高压实验，获取了氧化镍等温压缩、高压相变及电导率压力效应的新结果，并在实验数据的基础上，对其高压相变与电性及磁性变化关系及体弹性模量作了分析讨论。     

Phenomenological Scaling of Rapidity Dependence for Anisotropic Flows in 25 MeV/nucleon Ca＋Ca by Quantum Molecular Dynamics Model

Anisotropic flows （v1, v2, v3 and v4） of light fragments up to the mass number 4 as a function of rapidity are studied for 25 MeV/nucleon ^40Ca ＋ ^40Ca at large impact parameters by a quantum molecular dynamics model. A phenomenological scaling behaviour of rapidity dependent flow parameters vn （n = 1, 2, 3 and 4） is found as a function of mass number plus a constant term, which may arise from the interplay of collective and random motions. In addition, v4/v2^2 keeps to be almost independent of rapidity and remains a rough constant of 1/2 for all light fragments.     

An Artificially Garnet Crystal Materials Using In Terahertz Waveguide

A hypothesis is brought forward that the materials with low propagation loss in both optical and microwave band may exhibit good performance in terahertz （THz） band because THz wave band interspaces those two wave bands. For the purpose-of exploring a kind of low-loss material for THz waveguide, Lu2.1Bi0.9Fe5O12（LuBiIG） garnet films are prepared by liquid phase epitaxy （LPE） method on a gadolinium gallium garnet （GGG） substrate from lead-free flux because of the good properties in both optical and microwave bands. In microwave band, the ferromagnetic resonance （FMR） linewidth of the film 2△H = 2.8-5.1Oe; in optical band, the optical absorption coefficient is 600cm^-1 at visible range and about 100-170cm^-1 when the wavelength is longer than 800nm. In THz range, our hypothesis is well confirmed by a THz-TDS measurement which shows that the absorbance of the film for THz wave is 0.05-0.3 cm 1 and the minimum value appears at 2.3 THz. This artificial ferromagnetic material holds a great promise for magnetic field tunable THz devices such as waveguide, modulator or switch.     

A METHOD FOR FINDING POTENTIALS CORRESPONDING TO POLYNOMIAL-FACTOR EIGENFUNCTIONS IN QUANTUM MECHANICS

A method for finding potentials corresponding to polynomial-factor eigenfunc-tions is given for the Schr（?）dinger equation as an example.It is shown that theeigen-solutions for harmonic and Columb's potentials in quantum mechanics are the twoexamples which can be given by this method and some other examples are discovered.This method and some results of this paper may be useful for hadron structure mo-del theory.One of the examples is the equation in Ref.（4）which is derived fromBethe-Salpeter equation for the case that the straton is tightly bounded in certain po-tential well.When this method is applied to that equation for three dimensionalcentral symmetric potential V（r）=V₀—2（N+（1/2））β^-1（√V₆r²）+（V₆r⁶）, some resultsare obtained as shown in Fig. 2 in which λ′ must be considered as a linear function of m².The so called“quasic Regge trajectory”behavior is manifested.     

APPLICATION OF THE EIKONAL WAVE FUNCTION TO QUASIFREE SCATTERING

In this paper. we have used the Eikonal wave functionφ_E(r)=(2π)^-3/2 exp(ik.r)X(r)whereexp{-i/hv∫_-∞^zV(x,y,z,')dz'}and V=nk/m to investigate the quasifree scattering ⁶Li (p, pd)α with E_p=156 MeV,590MeV and 670 MeV. In V(x, y, z), the nuclear interaction and the Coulomb inte-raction are included. For the case of 156 MeV, the nuclear potential is taken to be the Woods-Saxon type.The result is shown in fig. 1. This result is compared with those obtained by themethod of partial waves. For the cases of 590MeV and 670MeV, a new method is used to describe thenuclear potential, and the results are showh in fig. 3 and fig. 4, respectively.