Study on υμ, υγ, Decays and CP Non-Invariance at Early Epoch of the Universe

We study the υ_μ and υ_γ decays in the early epoch of the universe. If m_υγ > 2m_e, there would be a CP asymmetry between υ_γ→e⁺+e^-+υ_e and υ_γ→e⁺+ e^-+ υ_e. The resultant CP non-invariance is a function of temperature and density and can reach l0^-7 for a reasonable temperature range, but it is noticed that if m_υγ > 2υ_μ～200 MeV, the CP non-invariance can be much larger.     

A Determination of Nucleon Form Factor Ratios Using Perturbative QCD

Using perturbative QCD in conjunction with CVC and standard electroweak theory, it is shown that at large Q², F₁ⁿ/F₁^P = F₂ⁿ/F₁^P = -0.69. The comparison with other results on form factor ratios from QCD sum rules and/or PQCD is carried out.     

Contribution of Quark Structure Term in Nucleon Electric and Magnetic Form Factors

The constituent quarks in the nucleon have always been considered as a point-like particle in the relativisticconstituent quark model. However its calculation results of GE^n agree poorly with the new experimental data. Theelectromagnetic structure of light front constituent quarks is considered in this paper. We find that the calculationresults have good agreement with the new experimental data of GE^n after considering the contribution of the quarkstructure term. This treatment seems to be able to improve the fit to experimental data of GEp/GMp,√Q2F2p/kpF1p,and GEn/GMn as well.     

The Friction and Diffusion Coefficients with Maxwellian Scatters

The Fokker-Planck coefficients for Coulomb interaction, or the friction coefficient (Δυ_α) (the average change in velocity) and the diffusion coefficient (Δυ_αΔυ_α), are evaluated by an appropriate variable change technique. This approach reduces the five-fold integral expressions of the Fokker-Planck coefficients to one-fold integral without meeting the divergence difficulties. A new Debye cutoff parameter Δυ_αmin, instead of the customary θ_min cutoff avoids the error incurred through the customary neglecting of velocity dependence of the Coulomb logarithm. The dominant terms of the new results are similar to Chandrasekhar's results. A non-dominant term, which can exceed the dominant one in the case of υ_α² > υ_βt²lnA is added for (Δυ_α||²).     

Top-Quark Condensate at Finite Temperature and Electroweak Symmetry Restoration

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.     

CHClF2在强红外激光作用下C2*d3Пg态的形成机制

用TEACO₂激光辐照CHCIF₂分子生成电子激发态C₂^*自由基,观察到斯旺带系的六个谱带。本文根据C₂分子态位能曲线的特点,提出C₂^*d³Π_g态的形成机制。C₂是少数较特殊的分子之一,其激发态b³Σ_g^-与第一激发态a关键词：     

A Discussion of the Question in Connexion with the Expansion of a Divergent Series Encountered in Calculating Nuclear 2υ-2β Decay Matrix Element

It is shown that the expansion and summation of the divergent series occurring in 2υ-2β decay calculation^[1,2] can be well-defined without mathematical flaw.     

Calculation of the Gluon Distribution Function Using Alternative Method for the Proton Structure Function

A calculation of the proton structure function F2(x,Q^2) is reported with an approximation method that relates the reduced cross section derivative and the F2(x, Q^2) scaling violation at low x by using quadratic form for the structure function. This quadratic form approximation method can be used to determine the structure function F2 (x, Q^2) from the HERA reduced cross section data taken at low x. This new approach can determine the structure functions F2(x,Q^2) with reasonable precision even for low x values which have not been investigated. We observe that the Q^2 dependence is quadratic over the full kinematic covered range. To test the validity of our new determined structure functions, we find the gluon distribution function in the leading order approximation with our new calculation for the structure functions and compare them with the QCD parton distribution functions.     

VO2薄膜表面氧缺陷的修复:F4TCNQ分子吸附反应

VO₂表面氧缺陷的存在对VO₂材料具有显著的电子掺杂效应, 极大地影响材料的本征电子结构和相变性质. 通过2, 3, 5, 6-四氟-7, 7', 8, 8'-四氰二甲基对苯醌(F₄TCNQ)分子表面吸附反应, 可以有效消除表面氧缺陷及其电子掺杂效应. 利用同步辐射光电子能谱和X射线吸收谱原位研究了修复过程中电子结构的变化以及界面的化学反应, 发现这种方式使得VO₂薄膜样品氩刻后得到的V³⁺失去电子成功地被氧化成原先的V⁴⁺, 同时F₄TCNQ分子吸附引起电子由衬底向分子层转移, 界面形成带负电荷的分子离子物种. 受电化学性质的制约, F₄TCNQ分子吸附反应修复氧缺陷较氧气氛退火更安全有效, 不会引起表面过度氧化形成V₂O₅.     

水溶性β-NaY(Gd)F4:Yb3+/Er3+纳米棒的水热合成及生物偶联

以聚乙烯亚胺(PEI)为表面活性剂,采用水热合成法,制得了表面氨基修饰的水溶性β-NaY(Gd)F₄:Yb³⁺/Er³⁺纳米棒,并对β-NaY(Gd)F₄:Yb³⁺/Er³⁺上转换纳米棒的制备方法、条件等进行了考察.结果表明,当Gd³⁺的引入摩尔分数为40%时,200 ℃下反应8 h即可获得纯β-NaY(Gd)F₄:Yb³⁺/Er³⁺纳米棒.利用X射线粉末衍射仪(XRD)、扫描电子显微镜 (SEM)、透射电子显微镜(TEM)、荧光光谱(PL)对样品的结构、形貌及光谱特性进行了表征.结构和形貌分析结果表明,制得的样品为单相β-NaY(Gd)F₄:Yb³⁺/Er³⁺纳米棒,纳米棒的截面粒径约为40 nm,平均长度约为210 nm.在980 nm波长激发下,样品的上转换发光光谱中出现了4个发射中心位于407,529,546,660 nm的发射带,分别对应于Er³⁺离子的²H_9/2→⁴I_15/2、²H_11/2→⁴I_15/2、⁴S_3/2→⁴I_15/2和⁴F_9/2→⁴I_15/2跃迁.采用戊二醛法,使β-NaY(Gd)F₄:Yb³⁺/Er³⁺上转换纳米棒表面的氨基与牛血清蛋白(BSA)分子中的氨基成功偶连在一起.利用紫外光谱分析(UV)和考马斯亮蓝法,对二者的偶联进行了证明.     

径向积分的解析计算

本文阐明的方法能方便地求出径向积分ⁿ₁^l₁F_Lⁿ₂^l₂(q)≡∫₀^∞> (R_n1^l₁(αr)jL(Kr)R_n2^l₂(αr)r²dr(q≡(K)/(α))的解析表达式。文中给出了L=0,1,2情况下各个径向积分的解析式,同时还以多重求和的形式络出了对各种量子数L,n₁,l₁,n₂,l₂适用的径向积分表达式。     

Calculations of the Spin-Lattice Coupling Coefficients Fij and Zij for MgO:Co2+ Crystal

According to a uniform and simple method of calculating spin-lattice coupling coefficients and the perturbation formulas of g_i factors and hyperfine structure constants A_i based on the cluster approach for 3d⁷ ions in cubic, tetragonal and trigonal octahedral crystal fields, the spin-lattice coupling coefficients F_ij (F₁₁, F₁₂, F₄₄), Z_ij (Z₁₁, Z₁₂, Z₄₄) and also g factor and hyperfine constant A for MgO:Co²⁺ are calculated by using the parameters obtained from the optical spectra without adjustable parameters. The calculated results show good agreement with the observed values. The difficulty in explaining the coefficients F_ij and Z_ij is therefore removed.     

The Universality of the Critical Dynamics of the Kinetic Ising Model on the Regular Fractals

The form of the universal scaling law of the critical dynamic exponent, z = D_ƒ + 2/υ, is found on a family of regular fractals by the exact TDRG method. Here, we generate a regular fractal by an anisotropic growing process. Identifying the growing probabilities as the interactions between Ising spins on the fractals, we map the growing probability clouds as a group of the anisotropic Ising Hamiltonians. Applying the RG transformations, we find that the systems of this group of Ising Hamiltonians can be described by two universal static correlation exponents υ₀ = ∞ and υ = 1. So, the growing processes proposed by us capture the essential features in the directed DLA simulations. The studies about their critical dynamic behaviours reveal that unlike the one-dimensional chain the critical dynamics of the kinetic Ising model on the regular fractals is universal. The further discussions show that there is a universal scaling law form of the critical dynamic exponent of the kinetic Ising model, z = D_ƒ + R_max/2υ, on the site models of the regular fractals with R_min = 2. Meanwhile, we discuss Daniel Kandal's correction to the formula of the,critical dynamic exponent in the TDRG method and show that our TDRG calculations are exact.     

Deforming the Travelling Wave Solutions of the KdV Equation to Those of the Generalized Fifth Order KdV Equation

Using some limiting procedures, the solutions of the fifth order KdV equation u_t + (μu²+ υu_xx + αuu_xx + βu_x² + γu³ + δu_xxxx)_x = 0 would degenerate into the solutions of a simple equation, say KdV equation. In this letter, we analyze the possibility of the inverse procedure of the limiting process mentioned above for the travelling wave solutions. The results show that the procedure for deforming a travelling wave solution of the KdV equation to that of the generalized fifth order KdV equation can be accomplished by some pure algebraic tricks. Moreover, this inverse procedure is not unique in general.     

Energy Spectrum and g Factors of α-A12O3:Ni2+ and Their Pressure-Induced Shifts

A unified calculation of the whole energy spectrum and g factors of the ground stateat normal pressure and their pressure-induced shifts for α-A1₂O₃:Ni²⁺ has been carried outon the basis of the theory of pressure-induced shifts and the diagonalization of the completed⁸ energy matrix adopting C_3υ symmetry. The calculated results are in very good agreementwith all the experimental data. The rates of change of all the levels with respect to variousparameters and the contributions to typical levels or splittings from various parameters havebeen calculated. The distinct differences of pressure-induced shifts of various levels are immediatelydetermined by their characteristic dependencies on -the parameters of interactions,and the pressure-induced shifts (especially those of t₂⁶e^{2 1}EÊ) have provided important or,crucial criteria for the correctness of the calculation and assignment of the energy spectrum of α-A1₂O₃:Ni²⁺.     

B_s → f_0 (980) Transition Form Factors Within the k_T Factorization Approach

In the paper, we apply the kT factorization approach to deal with the Bs → f0 (980) transition form factors in the large recoil regions, i.e. the small q 2 regions. For the purpose, we adopt the B-meson wave-functions ΨB , ΨB and δ that include the three-Fock states contributions to do our discussion. Although the scalar meson f0 (980) is widely perceived as the 4-quark bound state (scenario 2), but the distribution amplitudes of 4-quark states are still unknown to us, so we adopt 2-quark model (scenario 1) for scalar meson f0 (980) in our discussion. By varying the B-meson wave-function parameters within their reasonable regions, we obtain F0(0) = F+(0) = 0.20 ± 0.02, FT(0) = 0.24 ± 0.02. Our present results for these form factors are consistent with the light-cone sum rule results obtained in the literature.     

What About the Contribution from Reggeons in Hard Process of Strong Interactions?

We discuss in this paper the possible contributions from IR_ρ (ρ-reggeon associated with ρ meson) in DIS process on protons. Using results from phenomenological analysis of high energy π-N charge-exchange scattering process, we get the expression of effective propagator of IR_ρ and the coupling constant β_ρ between IR_ρ and light quarks. As a simple and concrete example, we use them to evaluate the contributions of ρ to F₂(χ, Q²) from charge-exchange photoproduction quark-pair process, γ^* + p → n + q_u + q_d(→ n + X), in HERA kinematical regions. For comparison, we also evaluate contributions both from pomeron and partons in the same process. The ratio of contributions in F₂(χ, Q²) from IR_ρ versus IP is larger than 1%, therefore, the former may be tested experimentaly.     

Reanalysis of the Z_c(4020), Z_c(4025), Z(4050) and Z(4250) as Tetraquark States with QCD Sum Rules

In this article, we calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion, and study the C γμ- Cγνtype scalar, axial-vector and tensor tetraquark states in details with the QCD sum rules. In calculations, we use the formula μ = (M 2X/ Y /Z-(2Mc)2)~(1/2) to determine the energy scales of the QCD spectral densities. The predictions MJ =2=(4.02+0.09-0.09) GeV, MJ =1=(4.02+0.07-0.08) GeV favor assigning the Zc(4020) and Zc(4025) as the JP C= 1+-or 2++diquark-antidiquark type tetraquark states, while the prediction M++J =0=(3.85+0.15-0.09) GeV disfavors assigning the Z(4050) and Z(4250) as the JP C= 0diquark-antidiquark type tetraquark states. Furthermore, we discuss the strong decays of the 0++, 1+-, 2++diquark-antidiquark type tetraquark states in details.     

The deuteron A(Q) structure function and the neutron electric form factor

We have measured the deuteron A(Q²) structure function in the momentum transfer region between 1 and 18 fm⁻². The accuracy of the data ranges from 2 to 6%. These measurements allow a sensitive test of theoretical predictions. We find that meson-exchange currents and relativistic corrections significantly improve the agreement between experiment and theory. We investigate the sensitivity of A(Q²) to the nucleon-nucleon interaction and to the neutron electric form factor G_Eⁿ(Q²). Our analysis shows that G_Eⁿ(Q²) can be extracted from these data with a significantly improved accuracy. The model dependence of this analysis is discussed.     

The Systematic Approximation and the Systematic Adiabatic Approximation for the Stochastic Systems Driven by O-U Noises

In this paper, we generalize the systematic approximation and the systematic adiabatic approximation developed by G. Schöner and H.aken^[1,2] to the stochastic systems driven by O-U noises. After eliminating the fast variables st, we introduce a new family of stochastic processes K_t^(υ) (υ≥2) in the equations for the order parameters vt. A typical model serves to illustrate how to derive the equation for the order parameter and how to calculate the statistical properties of the new stochastic processes K_t^(υ) (υ≥2). Some significant discussions and conclusions are given in Sec. V.