用推广的Skyrme力计算微观光学势

本文用同时描述原子核基态和激发态性质的推广的Skyrme力计算了²⁰⁸Pb等核素的微观光学势,并给出了每个核子光学势实部和虚部的体积分和均方根半径,还用所得到的光学势计算了弹性散射角分布和全截面。计算结果表明用推广的Skyrme力计算的光学势无论实部还是虚部比通常的Skyrme力均有明显的改进,在入射能量低于100MeV范围内能较好地符合实验。     

用扩展Skyrme力计算有限核微观光学势

本文讨论了用扩展Skyrme力和Hartree-Fock方程计算微观光学势的方法. 首先由变分原理导出了HF方程, 并用两种不同的方法得出了球形核光学势的计算公式, 然后对不同入射能量(0—350MeV)用八组Skyrme力参数计算了对称核¹⁶O、⁴⁰Ca及非对称核⁹⁰Zr的微观光学势. 结果表明其形状和随能量的变化趋势是合理的, 在中能区出现了"酒瓶底"形状, 同时明显地体现了壳效应.     

修正到υ2/c2的夸克相互作用等效势

我们分析了引进轴矢流交换来抵消自旋-轨道相互作用的必要性和可能性, 以及这个方法仍然存在的问题.     

密度矩阵对π－核光学位中泡利修正项的影响

π^－核光学位中的泡利修正项与密度矩阵密切相关. 本文分别用均匀费米气体模型、定域费米气体模型、修正的定域费米气体模型和壳模型谐振子波函数计算了O¹⁸的密度矩阵, 并由此研究了在Δ₃₃共振区(π分子动能为50～300MeV的区域)二级π^－核光学位中的泡利修正项. 对四种情况进行了分析、比较.     

Three Body Amplitude Analysis of the Process a2(1320)→π+π+π－

We analyze the decay amplitudes of the process a₂(1320)→π⁺π⁺π^－ using the tensor analysis method and show how to obtain three body amplitudes.     

A note on Ξc(3055)+ and Ξc(3123)+

The Babar Collaboration announced two new excited charmed baryons Ξ_c(3055)⁺ and Ξ_c(3123)⁺. We study their strong decays assuming they are D-wave states. Some assignments are excluded by comparing our numerical results with the experimental values of the total widths of Ξ_c(3055)⁺ and Ξ_c(3123)⁺. We also suggest some possible decay modes, which will be helpful to     

NaK(61Σ+)与H2碰撞传能中的H2的振转态分布

光学-光学双共振激发NaK至61Σ+高位电子态,研究了NaK(61Σ+)与H₂的电子-振转能量转移。利用相干反斯托克斯拉曼散射(CARS)光谱技术检测H₂的振转态分布。扫描CARS谱表明H₂在(1,1),(2,1),(2,2),(2,3),(3,1),(3,2),(3,3)和(3,5)振转能级上有布居。对于(3,1), (3,2), (3,3)和(3,5)能级,扫描CARS谱峰值直接给出布居数之比。对于(1,1), (2,1), (2,2)和(2,3)能级,扫描CARS谱峰值给出二个可能的布居数之比,利用一个速率方程组,由时间分辨CARS轮廓可以得到真实的比值。用n₁～n₈分别表示H₂的(3,1), (2,1), (1,1), (3,3), (2,3), (2,2), (3,2)和(3,5)能级上布居密度,得到n₂/n₁～n₈/n₁分别为0.51,0.97,0.45,0.18,0.10,0.26和0.31。利用Stern-Volmer公式,得到61Σ+态的总退布速率系数为(2.1±0.4)×10-10 cm3s-1, 由H₂各振转能级布居数之比,得到61Σ+-(1,1), (2,1), (2,2), (2,3), (3,1), (3,2), (3,3)和(3,5)转移速率系数(10-11 cm3·s-1单位)分别为5.4±1.6,2.8±0.8,0.6±0.2,1.0±0.3,5.6±1.7,1.4±0.4,2.5±0.8和1.7±0.5。     

MICROSCOPIC OPTICAL POTENTIAL CALCULATION BY THE MODIFIED SKYRME FORCES WITH THE t3ρα TERM

The real part and the imaginary part of the optical potential and their volume integrals per nucleon for ⁴⁰Ca and ²⁰⁸Pb are calculated on the basis of the modified Skyrme-forces with the t₃ρ^α term (α<1) which was developed recently. The calculated results and their comparison with the phenomenological optical potential and empirical values show that the nuclear force parameters of SKa and SKb are the best, SGI is the next and the others are rather bad.     

Study of D0→π－l+νl Decay

In this paper, the D⁰→π^－l⁺ν_l decay process is studied by applying light-cone QCD sum rules. The form factor of D→π transition is calculated by choosing a correlation function with a chiral current to eliminate the effect caused by the uncertainty of the twist-3 function of the pion. Therefore the calculated result of the form factor is improved, and the branching ratio of the D⁰→π^－l⁺ν_l decay process is consistent with the new experimental data.     

Analysis of Bs→φμ+μ- decay within supersymmetry

Motivated by the rst measurement on B(B_s→φμ⁺μ^-) by the CDF Collaboration, we study the supersymmetric e ects in semi-leptonic B_s→φμ⁺μ^- decay. In our evaluations, we analyze the dependences of the dimuon invariant mass spectrum and the forward-backward asymmetry on relevant supersymmetric couplings in the MSSM with and without R-parity. The analyses show that the new experimental upper limits of B(B_s→φμ⁺μ^-)from the LHCb Collaboration could further improve the bounds on sneutrino exchange couplings and (δ_LL^u)₂₃ as well as (δ_LL,RR^u)₂₃ mass insertion couplings. In addition, within the allowed ranges of relevant couplings under the constraints from B(B_s→φμ⁺μ^-), B(B→K^(*)μ⁺μ^-) and (B_s→φμ⁺μ^-), the dimuon forward-backward asymmetry and the di erential dimuon forward-backward asymmetry of B_s→φμ⁺μ^-are highly sensitive to the squark exchange contribution and the (δ_LL^u)₂₃ mass insertion contribution. The results obtained in this work will be very useful in searching for supersymmetric signals at the LHC.     

Probe the Strength of Annihilation In BS→π＋π－ Decays Within QCD Factorization

Using the method of QCD factorization, we calculate the branching ratio and the CP violation for pure annihilation decay B_S→π^＋π^－ in the Standard Model. Meanwhile, we employ an effective gluon mass resulted in the study of the infrared behaviour of gluon propagators to avoid the soft endpoint divergence. We find that the CP-averaged branching ratio is about 1.24×10^－7, and the penguin diagram contributions is dominant in this process. The direct CP violation parameter is about －0.05, while the mixing-induced CP asymmetry is a quite large number of 0.18. Once these quantities can be measured in the future LHC-b experiments, studying such a process will enrich our knowledge on the dynamics of the charmless hadronic decay of B-meson and the property of gluon.     

Integrability of AdS3×S3 Superstring

From the κ symmetric action of IIB string in AdS₃×S³ background given by Rahmfeld and Rajaraman, we derive the equations of motion. Then using the twisted dual transformation which was introduced by Hou et al. We construct the flat currents, and hence conserved non-local charge with one free parameter, for the Green-Schwarz superstring in AdS₃×S³. Thus we show the AdS₃×S³ string is integrable.     

Study of Ds±→μ±νμ at Belle

We present a preliminary measurement of the B(D_s→μν_μ) with the Belle
experiment at the KEKB collider. We select D_s→μν_μ decays with a method that provides a high-purity of the selected sample and an absolute measurement of the branching fraction. The results are based on a data sample of 550fb^－1 and are compared to similar measurements by other experiments as well as to the predictions of LQCD. We conclude with short prospects for improvements in the accuracy of the measurement.

     

Measurement of the τ Polarization Asymmetry in τ→a1 v→π±π0π0v Decay at Z0 Peak

The τ polarization asymmetry in τ→a₁v→π^±π⁰ π⁰v decay at Z⁰ peak is measured using data collected by L3 detector at LEP in 1992 and 1993, A_pol=－0.239±0.126±0.100, where the first error is statistical and the second systematic. And the effective electroweak mixing angle sin²θ_w=0.2197±0.0219 is derived.     

χ3+χ5介质中非束缚态空间亮孤子的传输行为

本文从理论上研究了主克尔型介质中非束缚态空间亮孤子的传输行为。数值计算结果表明:在主克尔型χ⁽³⁾+χ⁽⁵⁾介质中可以传输非束缚态空间亮孤子。传输稳定性与其背景平面波的横向渐近传播常数q和χ⁽³⁾,χ⁽⁵⁾系数有关,非平凡相位因子在三、五阶效应竞争中的平衡作用,是获得非束缚态空间亮孤子稳定传输的关键。     

100—300MeV3He(π－,n)2H反应的微观描述

本文将G.E.Brown等研究π^－核散射的Isobar模型推广应用到中能(π,N)反应的描述上,用唯象近似方法处理多体效应, 探讨了非表态修正、核子关联波函数以及出射核子扭曲效应对反应微分截面的影响, 计算了100—300MeV³He(π^－,n)²H反应角分布, 所得结果与实验基本一致.     

Franck--Condon factors and r-Centroids for the A 1∑+u-X1∑+g Band System of 107,109Ag2: Comparison of the Observed and Calculated Absorption Band Strengths

Franck-Condon factors and r-centrolds for the, A^1 ∑^＋ u-X^1∑^＋ 9 band system of ^107,109Ag2 are computed using Morse and Rydberg-Klein-Rees potentials for both lower and upper electronic states. The differences between the two sets of results are typically in the third decimal place for transitions involving vibrational levels with ν＇ and ν＂ up to about 15. Somewhat larger deviations appear for higher vibrational levels, but both sets of results follow the same pattern, which is to match well with the relative absorption band strength distribution in our experimental spectrum. The relative absorption band strengths are calculated by assuming that the electronic transition moment has only a weak dependence on the internuclear distance r. Good agreement between our measured and calculated absorption band strength ratios is found, which provides an excellent test of the calculated Franck- Condon factors and relative absorption band strengths. The r-centrold value for the （ν＇ = 0, ν＂ = 0） band is found to be approximately equal to the average value of r＇ and r＇＇e , indicating that the potentials of both states are not significantly aaharmonic around their minimum regions.     

相互作用玻色子模型的Dyson表示与（满壳）50(d5/2g7/2s1/2d3/2h11/2)12中子组态集体能谱的微观计算

本文从包括对力、四极对力及四极力的核子-核子有效相互作用出发,按照相互作用玻色子模型（IBM）的Dyson表示,对于（满壳）⁵⁰(d_5/2g_7/2s_1/2d_3/2h_11/2¹²中子组态的集体能谱进行了微观计算.我们在有效作用强度较广的取值范围内确定IBM玻色子及IBM哈密顿量的微观结构,并把这样得出的IBM哈密顿量对角化,分析了各有效作用项对能谱结构的影响.结果表明:在适当选择的有效作用强度下计算的振动谱与Cd¹¹⁰的实验结果符合较好.而且,通过调节有效相互作用中各强度参量,能够体现从振动谱到转动谱的过渡趋势.     

LiMBO3 : Dy3+材料的发光特性

采用固相法制备了LiM(M=Ca, Sr, Ba)BO₃ : Dy³⁺材料,并研究了材料的发光特性。LiM(M=Ca, Sr, Ba)BO₃ : Dy³⁺材料的发射光谱均呈多峰发射,对应于Ca,Sr,Ba,其主发射峰分别是Dy³⁺的⁴F_9/2→⁶H_15/2(484,486,486 nm),⁶H_13/2(577,578,578 nm)和⁶H_11/2(668,668,666 nm)跃迁。监测黄色发射峰时,所得激发光 谱峰值位置相同,主激发峰分别为331,368, 397,433,462,478 nm,对应Dy³⁺的⁶H_15/2→ ⁴D_7/2,⁶P_7/2,⁶M_21/2,⁴G_11/2,⁴I_15/2和⁶F_9/2跃迁。研究了敏化剂Ce³⁺及电荷补偿剂Li⁺、Na⁺和K⁺对LiM(M=Ca, Sr, Ba)BO₃ : Dy³⁺材料发光强度的影响。结果显示:加入敏化剂Ce³⁺提高了材料的发光强度,发光强度最大处对应的Ce³⁺浓度为3%;加入电荷补偿剂Li⁺、Na⁺和K⁺后,材料的发光强度也得到了明显提高,但发光强度最大处对应的Li⁺、Na⁺和K⁺浓度不同,依次为4%、4%和3%。     

ON THE MESONIC MOLECULES (αp,μ－) AND (αp,2μ－)

ACQM is applied to study the μ^－-mesenic molecules (αp,μ^－) and (αp,2μ^－).It is found that the ground state X²Σ⁺ of (αp,2μ^－) is the repulsive one and the ground state X¹Σ⁺ of (αp,2μ^－) is a bound state with the equilibrium proton-proton separation R_e=0.0078bohr and the minimum energy E=－551.78a.u..