High order corrections to the time-independent Born-Oppenheimer approximation II: Diatomic Coulomb systems

We study the bound states of diatomic molecular systems. We prove that if the nuclear masses are proportional to ε^?4 then certain eigenvalues and eigenvectors of the Hamiltonian have asymptotic expansions to arbitrarily high order in powers of ε, as ε→0. The zeroth through fourth order terms in the expansions for the eigenvalues are those of the well-known Born-Oppenheimer approximation. The fifth order term is zero.     

中性碳原子基态关联效应的多体理论计算

应用原子多体理论对开壳层原子中电子关联效应的有效哈密顿量及波算符的Goldston图进行了分析,在此基础上得到了计算有效哈密顿量的简单方法;以HFS模型为零级近似对中性碳原子基态的关联效应进行了计算并通过与实验结果及其他文献基于HF模型进行的计算相比较,得到了令人满意的结论。     

The Effect of Quark Mass and α-α Term on qq Condensation in QCD Vacuum

Beginning with the QCD Lagrangian in the global color symmetry model, we have derived a Hamiltonian including the lowest order current-current coupling. Taking instantaneous quadratic interaction kernel and using the Bogoliubov-Valatin transformation, we have got an effective Hamiltonian for computation. This Hamiltonian is similar to that introduced by Le Yaouanc et al., except that the α-α term has been considered here. We calculated the qq condensation in the BCS type of vacuum with quark mass and α-α term included. Our calculation shows that the value of qq condensation has increased by at least 10% with the α-α term included.     

Spectroscopy of the Ωccb baryon in the hypercentral constituent quark model

We extract the mass spectrum of the triply heavy baryon Ω_ccb using the hypercentral constituent quark model. The first order correction is also added to the potential term of the Hamiltonian. The radial and orbital excited state masses are determined, and the Regge trajectories and magnetic moments for this baryon are also given.     

铍原子基态交换-相关能的多体理论计算

到目前为止,几乎所有的关于原子基态的多体计算都是以Hartree-Fock(HF)模型为零级近似。本文将零级哈密顿量取为Hartree-Fock-Slater(HFS)型的,在双激发(两体)近似下,对Be原子基态交换-相关能进行了多体理论计算,得到了与实验及别的作者以HF模型为零级近似所作多体计算相符合的结果。计算表明,以HFS模型为零级近似,对闭合壳层原子基态亦可成功地进行多体计算。 关键词：     

A Perturbation Theory of Zener Transitions in Dissipative Driven Systems

The effect of inelastic interactions on the Zener transitions in dissipative driven systems has been investgated by conventional perturbation theory in adiabatic approximation. Two canonical transformations are used to simplify the model Hamiltonian. In zeroth order approximation, we reproduce the previous results. Moreover, our theory can be used to calculate easily the higher order correction terms that would be difficult to obtain in the previous theory.     

Interactions between heavy mesons and Goldstone bosons from chiral dynamics

We calculate the S -wave scattering lengths for charmed mesons scattering off Goldstone bosons and explore their quark mass dependence using the chiral perturbation theory up to next-to-leading order as well as a unitarized version of it. The quark mass dependence of all scattering lengths determined in a recent lattice calculation can be reproduced by the unitarized version. We also discuss signals of possible bound states in these observables.     

Lattice model calculations for SU(2) Yang-Mills theory in 1 + 1 dimensions

Lattice model techniques are employed to study the low-energy spectrum of SU(2) Yang-Mills theory in 1 + 1 dimensions. The Hamiltonian formulation of Kogut and Susskind is employed. The strong coupling expansion is carried to eighth order for a few of the lower-lying states. These expansions are extrapolated to the continuum limit using Padé approximants, both for finite quark masses and in the non-relativistic limit (quark mass goes to infinity). These methods succeed in giving a qualitative picture of the spectrum, but their quantitative accuracy is poor.     

Higgs interchange and bound states of superheavy fermions

Hypothetical superheavy fourth-generation fermions with a very small coupling with the rest of the Standard Model can give rise to long enough lived bound states. The production and the detection of these bound states would be experimentally feasible at the LHC. Extending, in the present study, the analysis of other authors, a semirelativistic wave equation is solved using an accurate numerical method to determine the binding energies of these possible superheavy fermion-bound states. The interaction given by the Yukawa potential of the Higgs boson exchange is considered; the corresponding relativistic corrections are calculated by means of a model based on the covariance properties of the Hamiltonian. We study the effects given by the Coulomb force. Moreover, we calculate the contributions given by the Coulombic and confining terms of the strong interaction in the case of superheavy quark bound states. The results of the model are critically analysed.     

A non-perturbative calculation of meson and baryon masses with a one-parameter potential

Using a non-perturbative method and a Hamiltonian with only one parameter which is fitted from charmonium, we calculate the masses of all mesons and the baryon ground state masses. In addition we calculate the ratios of the leptonic width of the 1^{? ?} heavy quark bound states. Some general theorems are checked and the accuracy of the method used to solve the Schrödinger equation is discussed. The over-all agreement of the results with experiment is very good.     

Generalized parton distributions of the photon for nonzero skewness

We present a calculation of the generalized parton distributions of the photon when there is nonzero momentum transfer both in the transverse and longitudinal directions. We consider only the contributions when the photon helicity is not flipped and calculate those at leading order in electromagnetic coupling α and zeroth order in the strong coupling αs. We keep the leading logarithmic terms as well as the quark mass terms in the vertex. By taking Fourier transforms of the GPDs with respect to the transverse and longitudinal momentum transfer, we obtain the parton distributions of the photon in position space.     

Ambiguities in zeroth order fermion mass matrices

The six quark Weinberg-Salam model with the symmetry of the three generation permutation group S₃ has an extra O(2) pseudosymmetry when the Higgs fields lie in an S₃ doublet. We use this model as a prototype to question the derivation of zeroth order relations between fermion mixing angles and fermion masses.     

The Vibrational Spectrum of Methane in an Extended Boson-Realization Model

The vibrational spectrum of methane, including both stretching and bending vibrations, is calculated in terms of an extended boson-realization model, by taking into account the interactions between vibrations up to the fourth order. The problem of removal of spurious states is discussed in detail. The term number in the Hamiltonian increases very fast as the interaction order increases. When the spurious states are removed from the configuration space, the effective Hamiltonian is not unique. We find a method to greatly simplify the T_d invariant Hamiltonian without any error. Fitting 45 experimental data with the Hamiltonian gives a root-mean-square energy deviation 3.96 cm^-1.     

The Cabibbo angle and the mass of thet-quark in anSU (2) L ⊗U (1) model with horizontal symmetry

Enlarging theSU (2) _L ?U (1) gauge theory with six quark flavours by anSU (3) _H horizontal symmetry, we calculate the Cabibbo angle and we obtain a mass relation for thet-quark by including one-loop corrections to the flavour diagonal zeroth order mass matrix.     

A Light-Cone QCD Inspired Effective Hamiltonian Model for Pseudoscalar and Scalar Mesons

Considering the one-gluon exchange interaction and phenomenological quark confinement potential, an improved light-cone effective Hamiltonian for mesons and the corresponding radial mass eigen equations in angular momentum representation is obtained. Solving the J = 0 eigen equations numerically and using a set of adjustable parameters, the obtained solutions for ground states and radial excited states can simultaneously describe both pseudoscalar and scalar flavour-off-diagonal mesons. Some radial excited states are also predicted and wait for experimental test. More results for the vector and axial vector mesons are expected.     

双光子激光器的量子理论

从双光子激光器三能级模型的微观哈密顿量出发,应用慢变幅度近似和双光子旋波近似,在双光子过程压倒其它辐射过程的情形下,导出二能级双光子模型的等效哈密顿量,从而建立三能级模型与二能级双光子模型的正确关系。得到的等效哈密顿量包含通常讨论中所忽略的光学斯塔克效应项,其系数在一般情形下可与等效互作用常数具有相间的数量级。根据这等效哈密顿量,应用Haken激光理论的标准方法研究定态的阈值,平均光子数,自生频移,光子统计和涨落,并与以前未计及光学斯塔克效应的结果作比较。 关键词：     

Does chiral symmetry breaking cause the Nucleon-Delta mass difference?

We critically review recent calculations of the Nucleon-Delta mass splitting in the QCD sum rule approach. Some calculations indicate aN-Δ mass splitting already to zeroth order QCD, i.e., only due to the chiral symmetry breaking quark condensate. We show that there is no indication of a mass splitting to zeroth order if optimal interpolating fields are used for theN and Δ, where optimal fields are those for which the continuum contribution is minimal.     

类锂体系激发态1s2 nd(n=3,4,5)精细结构和项能的理论计算

使用全实加关联(fullcorepluscorrelation缩写为FCPC)和里兹(Ritz)变分方法计算了类锂体系(Z=11—20)激发态1s2nd(n=3,4,5)的非相对论能量和波函数;包括动能修正、电子电子接触项、轨道轨道相互作用项以及Darwin项的相对论修正和质量极化项由全实加关联波函数的一阶微扰给出,量子电动力学(quantumelectronicdynamics缩写为QED)修正由有效核电荷方法和类氢公式计算;给出了高电离类锂体系激发态的激发能、精细结构和项能(termenergy),并 关键词： 类锂体系 全实加关联 精细结构 激发能     

Charm quark energy loss at RHIC

Heavy quark energy loss in a hot QCD plasma is computed taking into account the competing effects due to suppression of zeroth order gluon radiation below the plasma frequency and the enhancement of gluon radiation due to first order medium induced bremsstrahlung. The results suggest a surprising degree of cancellation between the two medium effects for charm quarks and provide a possible explanation for the null effect observed by PHENIX in the prompt electron spectrum in Au+Au at √s = 130 AGeV. In this paper only the main results for heavy quark energy loss will be presented. For more detailed version see [1] and references therein.