NOTE ON A MCMILLAN-LIKE Tc FORMULA

In this letter, we present an analysis to understand why the McMillan-like T_c fornula: T_c=1.134ωlog(1-1.02μ^*+0.476λ)exp{-1+1.604λ/λ-μ^*(1+0.604μ)}, proposed in a previous paper by the authcrs,applies to crystalline superconductors satisfactorily but Iess satisfactorily to non-crystalline ones.     

The Three-Pion Decays of the a1(1260)

We investigate the decay of a₁⁺ (1260)→π⁺π⁺π^- with the assumption that the a₁(1260) is dynamically generated from the coupled channel ρπ and KK^* interactions. In addition to the tree level diagrams that proceed via a₁⁺ (1260)→ρ⁰π⁺→π⁺π⁺π^-, we take into account also the final state interactions of ππ→ππ and KK→ππ. We calculate the invariant π⁺π^- mass distribution and also the total decay width of a₁⁺ (1260)→π⁺π⁺π^- as a function of the mass of a₁(1260). The calculated total decay width of a₁(1260) is significantly different from other model calculations and tied to the dynamical nature of the a₁(1260) resonance. The future experimental observations could test of model calculations and would provide vary valuable information on the relevance of the ρπ component in the a₁(1260) wave function.     

一个新的自由能函数对介电高弹薄膜的多组等双轴预拉伸下力电耦合实验的预测

当介电高弹聚合物薄膜被施以面内等双轴预拉伸后, 受到厚度方向的电压作用时, 薄膜在力场和电场共同作用下产生大变形. 电场采用Maxwell应力分析, 力场采用橡胶弹性模型分析. 拟合这类变形的常用橡胶弹性模型主要有Neo-Hookean, Arruda-Boyce, Gent等模型. 这些模型对实验数据的定量拟合存在不同程度的偏差. 通过对实验数据的分析, 结合数学方法, 提出了一个新的自由能函数模型. 通过该模型对VHB4905介电高弹聚合物薄膜的多组等双轴预拉伸电力耦合实验进行拟合, 并以Neo-Hookean, Gent模型作为对照, 结果与实验数据拟合很好, 比对照模型的偏差明显缩小.     

The Role of a1(1260) in π-p→a1-(1260)p and π-p→π-ρ0p Reactions Near Threshold

We report on a theoretical study of the π^-p→a₁^-(1260) p and π^-p→π^-ρ⁰p reactions near threshold within an effective Lagrangian approach. The production process is described by t-channel ρ⁰ meson exchange. For the π^-p→π^-ρ⁰p reaction, the final π^-ρ⁰ results from the decay of the a₁(1260) resonance, which is assumed as a dynamically generated state from the K^*K and ρπ coupled channel interactions. We calculate the total cross section of the π^-p→a₁^-(1260)p reaction. It is shown that, with the coupling constant of the a₁(1260) to ρπ channel obtained from the chiral unitary theory and a cut off parameter Λρ~1.5 GeV in the form factors, the experimental measurement can be reproduced. Furthermore, the total and differential cross sections of π^-p→a₁^-(1260)p→π^-ρ⁰p reaction are evaluated, and it is expected that our model calculations can be tested by future experiments. These reactions are important for the study of the a₁(1260) resonance and would provide further constraints on the properties of the a₁(1260) state.     

Vacuum Polarization Bubble Effects on the Triangle Relations for B Meson Charmless Decay Amplitudes

Assuming that factorization is valid and that contributions of the exchange, annihilation, and penguin-annihilation diagrams are negligible, we study the effects of the QCD vacuum polarization bubbles on the decay amplitudes of some B meson charmless decays into two light pseudoscalars. The bubbles have much less effects on B⁰→π⁺π^-, π^-K⁺, π⁰K⁰ than on B⁰→π⁰π⁰ thus the triangle relation √2A(B⁺→π⁺π⁰) = A(B⁰→π^-K⁺)/R_u+√2A(B⁰→π⁰K⁰)/R_u is changed slightly while √2A(B⁺→π⁺π⁰)=√2A(B⁰→π⁰π⁰)+A(B⁰→π⁺π^-) is altered significantly. This may indicate that in order to test or use these triangle relations other higher order QCD corrections should also be carefully taken into consideration.     

THE SYMMETRIC STRUCTURE OF EXCITED STATES OF 13ΛC AND INVESTIGATIONS OF THE ANGULAR DISTRIBUTIONS OF 13C(K-,π-)13ΛC*

Based on the meth SU₃ × SU₂ supermultiplet classification,we studied the symmetric compon-ents of 10.4 and 16.4 MeV configuration of the ¹³_ΛC hypernucleus by calculating the hypernucleus by calculating the angular distribution of ¹³C(K^-,π^-)¹³_ΛC^* in the framework of DWIA, and analysed the effects of varying the parameters on the angular distributions.     

取代基对稀土夹心双酞菁铥荧光特性的影响

利用稳态荧光和时间分辨荧光方法研究了三明治型酞菁铥的荧光特性及其浓度、激发波长和取代基对荧光特性的影响。实验发现:3种双酞菁铥的氯仿溶液在700 nm处具有较强的荧光发射,给电子基-OC₈H₁₇的加入使得酞菁大环上π电子的离域性增强,降低了π分子轨道的能级差;同时,烷氧基上非成键电子能够和共轭体系中的π电子相互作用,形成p-π共轭,进一步降低了π-π^*之间的能级差,从而使荧光谱中发射峰的峰位发生红移,峰的强度也有变化。3种酞菁铥化合物在700 nm左右的荧光具有两个寿命,分别为单体和聚集体产生的,随着浓度的降低,单体成分逐渐增多。     

THEORETICAL INVESTIGATION OF THE ISOSPIN VIOLATING HADRONIC TRANSITIONS Ψ'→Ψ(11P1)+π° AND T"→T(11P1)+π°

The isospin violating processes Ψ'→Ψ(1¹P₁)+π° and T"→T(1¹P₁)+π° are investigated in the framework of the multipole expansion in quantum chromodynamics. Using the rate of Ψ'→Ψ+π° as an input to determine the isospin violating vertex, we obtain the following branching ratios for the processes BR(Ψ'→Ψ(1¹P₁)+π°)～10^-6-10^-5, BR(T"→T(1¹P₁)+π°)～10^-5-10^-3 for M₁1_p1=1/9(5M₁3_p2+3M₁3_p1+M₁3_p0). These are too small to be detected in the present experiments.     

ON THE REACTION MECHANISM AND THE SELECTION RULE IN THE DOUBLE CHARGE EXCHANGE REACTION OF PIONS ON NUCLEI (DCX)-A STUDY OF THE CONNECTION BETWEEN THE 2β-DECAY AND DCX ON jP=O+ NUCLEI

It is shown that in the pion induced double charge exchange reaction on J^p=O⁺→O⁺ nuclei,there exists a possible new reaction mechanism π⁺(Δ⁰,Δ⁺⁺)π^- or π⁺(Δ^-,Δ⁺)π^- in so-called single step process,while that old speculative mechanism π⁺(N,Δ)π^- or π⁺(N,Δ)π^- is firbidden by a well-known selection rule which has been indicated in the theory of the nuclear 2β-decay.     

AlH~+离子5个Λ-S态和10个?态的光谱性质以及激光冷却的理论研究

利用考虑Davidson修正的内收缩多参考组态相互作用(icMRCI+Q)方法结合相关一致基组aug-ccpV6Z计算了AlH~+离子前两个离解极限对应的5个Λ-S态和10个?态的势能曲线.为了提高势能曲线的可靠性和精确性,计算中考虑了自旋轨道耦合效应、芯电子价电子相关和标量相对论修正以及将势能外推至完全基组极限.基于得到的势能曲线,获得了束缚和准束缚的4个Λ-S态和8个?态的光谱常数和振动能级,与已有的实验结果符合.计算了2(1/2)→X~2Σ_(1/2)~+和A~2Π_(3/2)→X~2Σ_(1/2)~+跃迁的跃迁偶极距.利用计算的精确的势能曲线和跃迁偶极矩,获得了2(1/2)~(第一势阱)(υ′=0, 1)→X~2Σ_(1/2)~+(υ′′)和A~2Π_(3/2)(υ′=0, 1)→X~2Σ_(1/2)~+(υ′′)跃迁的高度对角化分布的Franck-Condon因子(f_(00)和f_(11))和大的振动分支比;预测了2(1/2)~(第一势阱)(υ′=0, 1)和A~2Π_(3/2)(υ′=0, 1)态短的自发辐射寿命和窄的辐射宽度,这适合于AlH~+离子的快速激光致冷.所需的3束激光冷却波长都在紫外区域.这些结果表明了激光冷却AlH~+离子的可行性.此外,评估了自旋轨道耦合效应对光谱常数、振动能级和激光冷却AlH~+离子的影响.     

Analysis of 14C(π+, π-) 14O Reaction at 50 MeV

The ground states of ¹⁴C and ¹⁴O are described by a cluster wavefunction and the ¹⁴C_gs(π⁺, π^-) ¹⁴O_gs DIAS transition at 50 MeV is calculated in the Glauber theory. The results are in agreement with experimental data qualitatively and indicate that the effect of the l2 C core on the reaction is important.     

Pole Analysis on Unitarized SU(3)× SU(3) One Loop χPT Amplitudes

We analyze ππ-KK and πη-KK couple channel [1,1] matrix Padé amplitudes of SU(3)× SU(3) chiral perturbation theory. By fitting phase shift and inelasticity data, we determine pole positions in different channels (f₀(980), a₀(980), f₀(600), K₀^*(800), K^*(892), ρ(770)) and trace their N_c trajectories. We stress that a couple channel Breit-Wigner resonance should exhibit two poles on different Riemann sheets and meet each other on the real axis when N_c=∞. Poles are hence classified using this criteria and we conclude that K^*(892) and ρ(770) are unambiguous Breit-Wigner resonances. For scalars the situation is much less clear. We find that f₀(980) is a molecular state rather than a Breit-Wigner resonance, while a₀(980), though behave oddly when varying N_c, do maintain a twin pole structure.     

Absolute spectral distribution of soft X-ray emission from laserproduced gold plasma

Quantitative measurement of spectral distribution of soft X-ray emission from laser produced plasmas and estimation of X-ray conversion efficiency are reported. The X-ray emission from planar gold target irradiated by an Nd:glass laser was recorded using a high resolution transmission grating spectrograph. Spectral distribution of X-ray intensity was derived using calibrated film data and a deconvolution procedure to account for contribution of higher diffraction orders. Results of conversion efficiency per unit solid angle, at a laser intensity of ~4×10¹² W/cm² (λ_L = 1.054 μm), for 10< λ <80 Å and in the water window spectral region (23< λ< 44 Å) are presented. A three-fold increase in conversion efficiency was observed for second harmonic laser irradiation (λ_L = 0.527 μm) at an intensity of 8×10¹² W/cm²     

THE QUARK MASS EFFECT OF THE DISTRIBUTION AMPLITUDES IN γγ-EXCLUSIVE PROCESSES

In this paper we have analyzed the γ^*π°→γ, γγ→ππ and γγ→ρρ processes by using the sum rules of the distribution amplitude ФM(xi,Q²), which are obtained from the π°→γγ and the π→μν decay processes. Since the angular distributions of the γγ→π°π° and γγ→ρ_⊥ρ_⊥ amplitudes are sensitive to the shape of the distribution amplitude ФM(xi,Q²), there is a possibility to investigate the effect of the quark mass from the angular distributions of γγ→MM exclusive processes.     

The New Clue to Understanding fo(975) Meson From Ds Decays

Based on the understanding of nonleptonic decays of charmed meson, the relative ratio Br(D_s⁺→f₀(975)π⁺/Br(D_s⁺→фπ⁺) is calculated. We argue that only (ss) component of f₀(975) contributes to it dominantly. The numerical result proves f₀(975) to be almost a pure (ss) state if the newly measured resultant value of the decay is trustable, and the conclusion is very usefulinformation as a clue for clarifying up the puzzle of 0⁺⁺ meson f₀(975).     

ξ(2230) Is Likely to Be a Glueball

On the basis of the recent results of ξ(2230) → π⁺π^-, pp and ξ(2230) → K⁺K^-, K_sK_s, measured by the BES Collaboration in J/ψ radiative decays, combined with the PSI85 experiment of pp → ξ(2230) → KK we argue that because of its very narrow partial decay widths to nn and KK (less than 1 MeV), its large production rate in J/ψ radiative decays (BR(J/ψ → γξ> 2.3×10^-3), and its flavor-symmetric couplings to ππ and KK, the ξ(2230) is very likely to to be a J^PC= (even)⁺⁺ glueball.     

SrCO3:Mn2+绿色荧光粉的合成和发光性能

采用共沉淀法结合高温固相法,在碳还原气氛下合成了SrCO3:Mn2+绿色荧光粉,用XRD和荧光光谱分别对样品的结构和发光性能进行了表征.XRD结果证实,样品为单一斜方晶系的SrCO3相;荧光光谱检测表明,样品在267nm左右紫外线激发下,产生峰位位于547 nm的明亮绿光,对应于Mn2+的4T1(4G)→6A1(6S)...     

B→a0(1450)ρ(ω) Decays in Perturbative QCD Approach

In the two-quark model supposition for the meson a₀(1450), which can be viewed as either the first excited state (scenario I) or the lowest lying state (scenario II), the branching ratios and the direct CP-violating asymmetries for decays B→ a₀(1450)ρ(ω) are studied by employing the perturbative QCD factorization approach. We find the following results: (a) For the decays B^- → a⁰₀(1450)ρ^- and \bar{B}⁰ → a⁺₀(1450)ρ^-, their branching ratios have large
difference between two scenarios. Although their branching ratios are larger than other considered decay modes, their direct CP-violatingasymmetries in both scenarios are small. (b) For the decays B^-→ a^-₀(1450)ρ⁰ and \bar{B}⁰→ a^-₀(1450)ρ⁺, a⁰₀(1450)ρ⁰, a⁰₀(1450)ω, their branching ratios are close to each other between two scenarios, respectively. (c) Comparing with the decays \bar{B}⁰ →π⁰ρ⁰,π⁰π⁰, the decay \bar{B}⁰→ a⁰₀(1450)ρ⁰ receives a
larger branching ratio in each scenario, which is sensitive to the variation of the Cabibbo-Kobayashi-Maskawa angleα.