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1.
用多通道Landau-Zener方法计算了He++H-和Li++D-低能碰撞过程中电荷转移截面,碰撞体系的初态与末态间的耦合矩阵元由渐近方法得到。计算结果与最近的实验结果进行了比较  相似文献   

2.
The photoassociation reactions H+D^+ and H+ +D induced by the one- and two-colour laser pulses are theoretically studied. The reactions occur through two channels: (i) H(1S)+D^+ →HD^+, and (ii) H^+ +D(1S)→HD^+. The reaction probability through channel (ii) is higher than through channel (i). The populations of the products H^+ +D and HD+ and the ratio of H^+ +D to HD+ can be controlled by laser pulses. The two-colour laser pulses can more efficiently lower the dissociation probability and therefore enhance the yield ratio of the product HD+.  相似文献   

3.
We calculate the D→η transition form factor in light-cone sum rules by taking improved current correlators to avoid the pollution from the twist-3 wave function. We get consistent results of the D+→η(′)l+νl decays with the experimental data. By comparing the difference between the results of the branching ratios of D+→η(′)l+νl from a two-pole parameterization model and from a BZ parameterization model, we find that the two-pole model and the BZ model are comparably believable. One way is supposed for the de...  相似文献   

4.
Low-energy scattering of D ^*+ and D1^0 meson is studied using quenched lattice QCD with improved lattice actions on anisotropic lattices.The threshold scattering parameters,namely the scattering length a 0 and the effective range r 0,for the s-wave scattering in J P = 0 - channel are extracted: a 0 = 2.52(47) fm and r 0 = 0.7(1) fm.It is argued that,albeit the interaction between the two charmed mesons being attractive,it is unlikely that they can form a shallow bound state in this channel.Our calculation provides some useful information on the nature of the newly discovered resonance-like structure Z + (4430) by the Belle Collaboration.  相似文献   

5.
We analyse the vertex D^*D^*ρ with the light-cone QCD sum rules. The strong coupling constant gD^*D^*ρ is an important parameter in evaluating the charmonium absorption cross sections in searching for the quark-gluon plasmas. Our numerical value for the gD^*D^*ρ is consistent with the prediction of the effective SU(4) symmetry and vector meson dominance theory.  相似文献   

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In contrast with B0-ˉB0, Bs-ˉBs mixing where the standard model(SM) contributions overwhelm that of the new physics beyond standard model(BSM), a measured relatively large D0-ˉD0mixing where the SM contribution is negligible, definitely implies the existence of the new physics BSM. It is natural to consider that the rare decays of D meson might be more sensitive to new physics, and the decay mode D0→μ+μ-could be an ideal area to search for new physics because it is a flavor changing process. In this work we look for a trace of the new physics BSM in the leptonic decays of D0. Concretely we discuss the contributions of unparticle or an extra gauge boson Z while imposing the constraints set by fitting the D0-ˉD0mixing data. We find that the long-distance SM effects for D0→lˉl still exceed those contributions of the BSM under consideration, but for a double-flavor changing process such as D0→μ±e, the new physics contribution would be significant.  相似文献   

8.
用全相对论量子力学方法计算了电子组态为[Rn]5f26d17s1的U的全部214个电子状态的能级,基态为5K5。设UO2为线型(R∞h),U和O2均为基态,则UO2的可能电子状态有3,5,7Σ-g,3,5,7πg,…。UO2的基态不大可能为1Σ+g。  相似文献   

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利用皮秒Nd:YAG激光器泵浦的光学参量发生傲大器作激发源,获得了NO分子在460~570nm波长范围内的多光子离化谱,测量了离化信号随激光强度的关系,其近五次方关系表明在460~570nm波长范围内NO分子吸收5个光子而离化。通过对谱线的归属,确认在此波长范围内,NO分子的离化过程是通过高激发态D^2∑的共振增强的多光子离化过程。用最小二乘法拟合,获得了D^2∑态的基振动频率和相互作用的力常数。  相似文献   

12.
The decays of J/ψ → μ^+μ^- and J/ψ → e^+e^- are studied by Monte-Carlo simulation, based on the Beijing Spectrometer (BES)Ⅲ offtine software system. The methods of determination of the J/ψ event number via J/ψ → μ^+μ^- and J/ψ → e^+e^- are presented, respectively. These methods can be used to determine the J/ψ event number for the coming BESⅢ J/ψ data sample.  相似文献   

13.
The vector correlations between products and reagents for the reactions Ne+H2+, Ne+D2+, and Ne+T2+ are calculated by means of the quasi-classical trajectory method on a new potential energy surface constructed by Lfi et al, [J. Chem. Phys. 2010 132, 014303]. The polarization-dependent differential cross-sections (27π/σ)(dσ00/dωt), (2π/σ)(dσ20/dwt), (27π/σ)(dσ22+/dwt), and (2π/σ)(dσ21-/dwt), and the distributions of P(θr), P(φ), and P(θr, Cr) are calculated. The isotopic effect, which is associated with the difference in mass factor among the three reactions, is revealed.  相似文献   

14.
许多同学认为高中物理特别难学;学习时像雾里看花,听听简单,做做较难,考考完蛋.其实物理究竟是"悟理"还是"雾里",取决于同学们对自然现象的领悟程度和正确的学习方法;只要学习方法得当,处理好"what""how""why'的问题,改变学习态度,注重物理概念,坚持知识积累,积极反思总结,保持虚心善问,注意解题细节,就会取得好成绩.笔者结合多年教学经验,从六个方面谈谈高中物理的学习方法.  相似文献   

15.
Within the framework of a nonlinear chiral Lagrangian the mass spectra and the decay properties of 0^++ states below 2 GeV are studied. Assuming that f0(980), a0(980), K0(1430), and f0(1500) comprise an SU(3) nonet, we make a detailed prediction about the static properties of the 0^++ mesons. The substructure analysis of these states in terms of two- and four-quark components as well as a glueball component is carried out. We also consider the interaction Lagrangian and provide a preliminary study of the strong and radiative decays of the 0++ mesons. The scalar glueball masses and partial widths are also presented. In view of the fact that few data of 0++ mesons are clearly given in the present PDG (Particle Data Group) list and that the four-quark content of mesons is a hot issue both experimentally and theoretically, the predicted results of the paper may be helpful for upcoming experimental and theoretical studies of these mesons.  相似文献   

16.
美国国家标准技术研究所(NIST)的数据加密标准DES连续使用了20年之后,庞大的并行网络电脑攻击和特定的“DES—Cracking”硬件攻克使其安全性受到了威胁,因此NIST决定用AES(高级加密标准)替代DES,并选择Rijndael作为AES的算法。来自比利时的两位密码专家开发的Rijndael算法汇聚了安全,性能,效率,易用和灵活等优点,使它成为AES最合适的:选择,Rijndael在不同硬件和软件运行环境下表现出始终如一的良好性能,而无论这些环境是否有反馈模式,它的密钥设置时间相当出色,密钥的灵敏性也不错。Rijndael非常低的内存需求也使它很适合用于受限环境中。Rijndael的操作简单,并可抵御强大和实时的攻击。  相似文献   

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YAG晶体中Cr^3+→Tm^3+,Er^3+→Tm^3+的能量转移   总被引:5,自引:1,他引:4  
黄莉蕾  王彦起 《光学学报》1994,14(9):31-935
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19.
类镍Hf^44+,Ta^45+,W^46+,Re^47+,Pt^50+,Au^51+能级结构…   总被引:3,自引:3,他引:0  
本文用多组态Dirac-Fock(MCDF)法计算了类镍Hf^44+、Ta^45+、W^46+、Re^47+、Pt^50+、Au^51+能级的精细结构和n=3-4偶极跃迁辐射的振子强度,得到了和实验符合得相当好的结果(对有实验数据的跃迁波长而言),并对组态的选取、核模型和、Breit修正和QED效应作了讨论,指出对于本文研究体系,QED效应对跃迁的贡献可以忽略。  相似文献   

20.
In order to explore the isotope effect on stereo dynamics, we investigate the trajectory calculations of Ar+H2+/D2+/T2+ and Ar+T2+ reactions on the ab initio potential energy surface constructed by us and calculate the distributions of product polarization P(θr), P(r) and four generalized polarization-dependent differential cross-sections. The product rotational alignment parameters (P2(j' · k)) for the title reactions are compared and discussed with mass factors. Furthermore, the angular distributions of the product rotational vectors in the form of polar plot in θr and r are presented. The results indicate that the stereo dynamics properties of the title reactions are sensitive to the mass factor.  相似文献   

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