类氖离子中的能级交叉及其对辐射光谱的影响

本文利用基于相对论多组态Dirc-Fock理论方法的程序包GRASP92以及新近发展的计算辐射跃迁的程序REOSS99，通过对电子关联效应、驰豫效应的系统考虑，计算了类氖等电子系列 (Z=21-92) 离子2p6, 2p53l, 2s2p63l(l=0,1,2)的能级结构和各能级间E1跃迁的波长以及跃迁几率；基于以上计算，详细研究了由于强组态相互作用引起的具有相同宇称和总角动量的能级间的交叉现象及其强组态相互作用对辐射跃迁几率的影响。     

类锂等电子系列高位三激发态2p2np4So能量和到1s2pmp4P态的辐射跃迁

利用多组态相互作用方法及Rayleigh-Ritz变分法,计算了类锂离子2p²np⁴S^o(n=2—4)和1s2pmp⁴P(m=2,3)的能量.运用截断变分方法得到能量的改进量.计算了相对论修正、质量极化效应,从而获得了高精度的能量计算值.同时还计算了该系统之间的辐射跃迁波长、振子强度和辐射跃迁率.计算结果与实验符合得很好. 关键词： 三激发态 类锂离子 振子强度 辐射跃迁     

类锂等电子系列高位三激发态2p2np4So能量和到1s2pmp4P态的辐射跃迁

利用多组态相互作用方法及Rayleigh-Ritz变分法,计算了类锂离子2p2np4So(n=2-4)和1s2pmp4P(m=2,3)的能量.运用截断变分方法得到能量的改进量.计算了相对论修正、质量极化效应,从而获得了高精度的能量计算值.同时还计算了该系统之间的辐射跃迁波长、振子强度和辐射跃迁率.计算结果与实验符合得很好.     

NⅡ离子2p4f—2p3d辐射跃迁概率的理论研究

在全相对论理论框架下，利用多组态Dirac-Fock(MCDF)方法，系统计算了NⅡ离子2p4f—2p3d的辐射跃迁概率，得到的结果与已有实验值符合很好.具体计算中，详细分析了相对论效应、电子关联、弛豫效应、Breit相互作用和量子电动力学(QED)效应对能级精细结构及辐射跃迁概率的影响.结果表明：相对论效应、电子关联和弛豫效应对NⅡ 2p4f-2p3d辐射跃迁概率有很重要的影响,考虑了这些效应后计算值得到明显改善.     

非相对论性和相对论性原子组态相互作用理论——激发能量和辐射跃迁几率

我们建立的非相对论性和相对论性原子组态相互作用理论计算方法可用来计算低度激发态的激发能量和辐射跃迁几率(包括允许跃迁和禁戒跃迁)。为了检查我们的计算程序,分别用两种方法计算了氦原子N=2激发态的激发能和相应的辐射跃迁几率。结果表明:非相对论性理论和相对论性理论计算结果基本一致。原子激发能量的精度为千分之几,振子强度的精度为百分之几。上述原子组态相互作用理论方法可用于计算任何原子或离化态原子。 关键词：     

氦原子单激发和双激发态里德伯系列的相对论能量计算

采用Rayleigh-Ritz变分方法和组态相互作用方法，并进一步考虑相对论修正和质量极化效应，研究了氦原子单激发和双激发态里德伯系列的相对论能量，计算结果与其他理论和实验符合得很好.此外，还计算了该系统之间的振子强度、辐射跃迁率及跃迁波长，振子强度三个规范的计算结果显示出很好的一致性. 关键词： 氦原子 变分计算 振子强度 辐射跃迁率     

硼原(离)子内壳激发高自旋态能级和辐射跃迁

采用Rayleigh-Ritz变分方法计算了B原子(离子)内壳层激发高自旋态(~(4,5,6)L,L=S,P)里德伯系列的能量和精细结构劈裂,利用截断变分方法改进非相对论能量,并利用一阶微扰理论计算了相对论能量修正和质量极化效应修正,利用屏蔽的类氢公式计算了量子电动力学效应和高阶相对论效应,从而得到了高精度的组态能量.利用精确计算的波函数,计算了这些高自旋态的电偶极辐射跃迁波长、振子强度和辐射跃迁概率.通过长度规范和速度规范计算的振子强度的一致性证明了本文计算的波函数是精确的.相比其他理论计算结果,本文计算的高自旋态的能级及跃迁波长数据与实验数据符合得更好.对于一些高位的内壳层激发高自旋态,相关的能级和跃迁数据为首次报道,本文的计算结果对相关实验光谱谱线标定具有重要意义.     

PtⅢ离子5d^8—5d^76P跃迁的极紫外光谱计算

本文运用多组态Hartree-Fock加相对论修正方法(MCHFR)计算了PtⅢ离子5d~8-5d~76p跃迁的光谱,得到了有关光谱数据如波长、振子强度和辐射跃迁几率,并就计算结果进行了简要分析.     

类氦离子2p3p3Pe双激发态等电子系列的能级和精细结构

采用Rayleigh-Ritz变分法及组态相互作用,并考虑相对论修正和质量极化效应,研究了类氦离子等电子系列(Z=2～16)双激发态2p3p3Pe的相对论能量和辐射跃迁波长,并计算了该系统的精细结构.计算的结果与Drake等人的理论计算符合得很好.     

Sc~(17+)、Sc~(18+)和Ti~(18+)、Ti~(19+)光谱波长和辐射跃迁几率的多组态HXR计算

本文用多组态HXR自洽场方法和优化径向积分方法相结合计算了类Li离子Sc~(18+),Ti~(19+)和类Be离子Sc~(17+),Ti~(18+)与软X射线激光研究有关的谱线波长和辐射跃迁几率     

Chiral Lagrangians and the Transition Amplitude for Radiative Muon Capture

 The transition operator for the radiative capture of mesons by protons is constructed starting from a chiral Lagrangian of the system obtained within the approach of hidden local symmetries. The transition operator is gauge invariant and its hadron radiative part satisfies exactly two relevant continuity equations. Received October 16, 1998; accepted for publication February 23, 1999     

Cancellation of infrared divergences in non-Abelian gauge theories

We investigate the infrared problem for non-Abelian gauge fields. Specifically, we show that the transition rate for fermion-fermion scattering suitably averaged over the colors of the fermions is infrared finite to lowest non-trivial order. The finite radiative correction due to soft bosons is given explicitly.     

Gauge hierarchy in the presence of discrete symmetry

We discuss the gauge hierarchy problem in theories that posses an additional discrete symmetry. As examples, we consider two models based on the gauge groups U(1)_L×U(1)_Rand SU(2)_L×SU(2)_R×U(1), with parity transformation as the discrete symmetry. By employing a minimal choice of Higgs multiplets there is no freedom, in the semi-classical approximation, to arrange for an arbitrary hierarchy. Either one has a left-right symmetric phase (no hierarchy) or a totally asymmetric phase (infinite hierarchy). It is shown that radiative corrections, à la Coleman-Weinberg, do not smooth out the transition region separating the two phases. A finite gauge hierarchy is not realized.     

Comments on intermediate-scale models

Some superstring-inspired models employ intermediate scales m₁ of gauge symmetry breaking. Such scales should exceed 10¹⁶ GeV in order to avoid prima facie problems with baryon decay through heavy particles and non-perturbative behaviour of the gauge couplings above m_I. However, the intermediate-scale phase transition does not occur until the temperature of the Universe falls below O(m_w), after which an enormous excess of entropy is generated. Moreover, gauge symmetry breaking by renormalization group-improved radiative corrections is inapplicable because the symmetry-breaking field has no renormalizable interactions at scales below m_I. We also comment on the danger of baryon and lepton number violation in the effective low-energy theory.     

Radiative decays of φ meson and nature of light scalar resonances

Physics of Atomic Nuclei - We show on gauge invariance grounds that a new threshold phenomenon has been discovered in the radiative decays φ → γa 0 → γπ 0 η and...     

Field-theoretical treatment of approximations to radiative transitions in atoms

Starting with a field-theoretical many-body definition of eigenvalues and radiative transition matrix elements for atomic systems, a systematic approach is taken to approximations of the exact results. The guiding principle is the maintenance of gauge invariance (GI) in radiative transition S matrix elements. At the level of the one Coulomb exchange approximation in both the one-electron and the electron-hole propagator kernels, one obtains the well-known Hartree-Fock (HF) and random phase approximations (RPA). A detailed discussion and comparison of various approaches to RPA is made, in the case of both N and N ? 1 electron shielding (the regular HF and HF with frozen relaxed core—FRC). In the former case, a new and considerably simpler form of the RPA equations are obtained than heretofore proposed equivalent forms. Finally, a different approximation than the usual HF and RPA, involving higher-order correlations, is developed to illustrate how such approximations can be systematically generated.     

Ward identities and radiative corrections in QED with conformal gauge

A model of QED with conformally invariant gauge is considered. This gauge, being essentially nonlocal, is written in a local form by means of two nonphysical scalar fields. Using the BRST symmetry and the additional residual symmetry, a system of Ward identities is derived. These Ward identities are applied to prove the renormalizability of the model as well as to investigate the radiative corrections. A new class of conformal anomalies arises, connected with the absence of radiative corrections to the propagators including auxiliary fields.     

Calculation of radiative properties of nonequilibrium hydrogen plasma

A computer program called NEQRAP is described that calculates the radiative properties of nonequilibrium ionized hydrogen. From the given electron temperature, electron density, and atom density values (which do not necessarily satisfy the equilibrium relationship) and intensities of incident radiation, the non-Boltzmann populations of electronic states are computed by solving the equation of quasi-steady- state population distribution. Emission and absorption coefficients are determined as functions of wavelength by invoking the principle of detailed balance between the upper and lower states of each radiative transition. Radiative transport through the medium is computed assuming a one-dimensional uniform slab. The rate of ionic reaction is also computed. When used on a sample case, the program shows that there is a large difference between the calculated intensities of radiation emitted by a bulk of equilibrium and nonequilibrium hydrogen. Accuracy of the program is estimated to be better than 10%.     

结构相变的规范场理论

 本文首先从场论的观点出发，构造了完整晶体的拉氏函数——晶体声子场的拉氏函数。利用晶体声子场在局域群G=SO(3)下的对称性破缺，引入了缺陷规范场。借助于场论中的真空对称性自发破缺和缺陷规范场理论，很自然地把缺陷引到结构相变的研究中。我们给出了相变温度θ_c，入点的热容量的跃变值ΔC_v，及序参数Φ_i的计算公式。从公式中，明显可看出缺陷对相变温度、热容变化值及序参数的影响。另外，我们确定了缺陷规范场理论中的耦合常数g。最后，我们给出了由压力引起的结构相变（如冲击相变）的一种可能的机理。