相对论夸克模型对重夸克偶素质量谱的研究

介绍了量子场论中基于准势途径的一个相对论夸克模型,并使用这个相对论夸克模型计算了重夸克偶素的质量谱.显示这个相对论夸克模型可较好地拟合实验上肯定的质量谱数据. A relativistic quark model based on the quasipotential approach in quantum field theory is briefly introduced, and by using this model, heavy quarkonium mass spectra are calculated in detail. It is shown that such a model can give results which are in agreement with the observed experimental data on the mass spectra.     

矢量-标量混合禁闭势模型时的重夸克偶素

本文用考虑了相对论修正的势模型计算重夸克偶素的能谱、轻子宽度和辐射跃迁宽度. 在模型中我们假定: 矢量型禁闭和标量型禁闭同时存在, 在远距离标量型禁闭为主, 在近距离矢量型禁闭为主. 在这个假定下我们得到了与实验符合得较好的精细分裂值.     

t夸克偶素能谱的计算

本文利用考虑胶子质量的重夸克偶素位势计算了t夸克偶素的能谱。 关键词：     

相对论效应对有限温下重夸克偶素的性质的影响

考虑相对论修正对重夸克偶素结合和分解所产生的作用，计算了重夸克偶素在热力学环境中的临界性质，并与非相对论模型理论进行了比较．     

洛伦兹规范条件下对单胶子夸克势的QCD非微扰修正形式

在洛伦兹规范条件下,导出了具有平移不变性的双胶子两点函数真空平均值.利用所获得的双胶子真空期待值,给出了对微扰单胶子交换夸克–夸克势、夸克–反夸克对湮没和夸克–反夸克对激发势的最低阶非微扰QCD修正形式.     

相对论夸克模型和N–Δ能量劈裂

基于相对论夸克模型,在夸克层次上研究了N-Δ的质量和二者的能量劈裂,通过引入了赝标量π介子云效应,得到了π和核子之间的耦合常数g_πNN,以及单胶子交换势和单π介子交换势分别对N-Δ能量劈裂的贡献,计算结果较好地与实验值得到了吻合.另外我们还比较了相对论与非相对论夸克模型在处理上的不同.     

胶子有效质量对重夸克势的影响

本文采用椭球袋模型讨论胶子有效质量对重夸克势的影响.我们分别计算了胶子有效质量0,0.2,0.4,0.6和1.0GeV时的重夸克势.计算结果表明,除汤川势外,势仍近似地呈线性,随着胶子有效质量的增加,斜率逐渐减小.     

重夸克偶素中的色屏蔽效应

将夸克-反夸克的禁闭位选为含有色屏蔽效应的禁闭势,计算了它对重夸克偶素cc和bb能谱的影响.与通常选用的线性禁闭势相比,含色屏蔽效应的禁闭势对ψ(cc)的高激发能级的轨道角动量可给出不同的预言,并且对ψ能级的轻子衰变宽度有明显的改进.     

核力的手征夸克-孤子模型理论

本文简短地描述了含单胶子交换的手征夸克孤粒子模型;将此孤粒子模型里所确定的夸克-胶子耦合常数及所解得的夸克波函数,输入到相对论的两夸克集团理论,研究了两核子系统问题.本文完整地考虑了夸克交换核中的动能和相对运动能量项,由此改进了~3S_1道和~1S_0道的相移.相移与Arndt等人的实验相移基本一致.计算结果表明,单胶子交换和夸克交换提供短程排斥势,手征场则提供了中、长程吸引势.     

粲夸克偶素和b夸克偶素的色屏蔽和分解

用非相对论的色屏蔽势模型研究粲夸克偶素和b夸克偶素束缚态的结合和分解.用两种参数化形式的位势,计算了在热力学环境中的色屏蔽长度.结果表明,临界屏蔽长度r与位势的形式有密切的关系.     

High-energy photons from passage of jets through Quark-Gluon plasma

We calculate the production of high-energy photons from Compton scattering and annihilation of a quark jet passing through a quark gluon plasma produced in a relativistic heavy ion collision. The contributions are large and reflect the momentum distribution of the jets and the initial conditions of the plasma.     

夸克和弦模型中非奇异轻介子的类雷吉谱(英文)

本工作重新考察了相对论弦模型和准相对论夸克模型中轻介子的类雷吉谱。基于辅助场技术,提出了非奇异轻介子的一个解析质量公式,由此推导出了一个准线性的Regge-Chew-Frautschi轨迹关系,并将此关系用相应介子的实验数据（PDG）进行了检验。检验结果表明,和实验观测数据比较,夸克模型对介子质量的预言与弦模型的相符,但在角动量较大时,夸克模型的预言稍微优于弦模型。We revisit the Regge-like spectra of light mesons in the relativistic string model and the simirelativistic quark model. An analytical mass formula is proposed for light mesons based on the auxiliary field technique, and a quasi-linear Regge-Chew-Frautschi plot with flavor dependence is derived and verified with the experimental data(PDG) for light mesons.The results show that the quark model predictions for meson masses agree with those of the string model, but are slightly better when the angular momentum is relatively large as compared with the observed data.     

Masses of heavy tetraquarks with hidden charm and bottom

The properties of light and heavy mesons, baryons and tetraquarks are discussed within a QCD-motivated relativistic quark model. The results for the mass spectra, electroweak properties and Regge trajectories of hadrons are presented.     

Low-energy properties of hadrons in the relativistic quark model

The properties of light and heavy mesons, baryons and tetraquarks are discussed within a QCD-motivated relativistic quark model. The results for the mass spectra, electroweak properties and Regge trajectories of hadrons are presented.     

Heavy Quark Potential and Quarkonium Spectrum in Nonperturbative pNRQCD

The charmonium and bottomonium mass spectra are investigated systematically in potential nonrelativistic QCD with the heavy quark potential computed by lattice QCD simulations nonperturbatively. The potential consists of a static potential and relativistic corrections classified in powers of the inverse of heavy quark mass m, and the effects of the O(1/m) correction, the O(1/m ²) spin–orbit and spin–tensor corrections on the mass spectra are examined systematically. The pattern of the mass spectra is found to be in fairly good agreement with the experimental data, in which the O(1/m) correction gives an important contribution.     

Production of top quark pairs in association with a hard gluon to order \alpha_s^2

The production of top quark pairs accompanied by a hard gluon in annihilation is studied including next-to-leading order corrections in the strong coupling. At leading order, the fraction r of events with respect to all events is computed analytically as a function of the minimal gluon energy. Next-to-leading order results for r are given for center-of-mass energies of 0.5 and 1 TeV. We further calculate the differential distribution of r with respect to several variables, including the top quark energy and the invariant mass. We then investigate how our results depend on the choice of the renormalization scheme for the top quark mass by comparing results expressed in terms of either the pole mass or the mass. Finally we estimate the sensitivity of the fraction r on the value of the running top quark mass at a scale of 1 TeV. Received: 7 April 1999 / Published online: 12 August 1999     

Spectroscopy of Baryons as Relativistic Three-Quark Systems

We present results from a study of baryon spectral properties within a relativistic constituent-quark model. In particular, we demonstrate the performance of a universal quark model for all light-, strange-, and heavy-flavor baryons with regard to their spectroscopy. Thereby we produce insights into the effective interaction between constituent quarks of the various flavors up, down, strange, charm, and bottom. The relativistically invariant mass spectra are obtained by two different methods for calculating the microscopic three-quark systems: a stochastic variational method, solving the eigenvalue problem of the invariant mass operator expressed by differential equations, and a Faddeev integral-equation method, adapted to treating long-range interactions, such as the quark confinement. The corresponding results agree very well, generally within a few percents. Taking into account relativistic effects through Poincaré invariance of the mass operator, or equivalently of the Hamiltonian, turns out to be of utmost importance.     

Spectra of baryons containing two heavy quarks

Doubly heavy baryons, i.e., the baryons containing two heavy quarks are treated in the adiabatic approximation, considering the motion of the light quark as a relativistic motion. The binding energy and mass spectra of doubly heavy baryons are calculated solving the two-center Dirac equation the one-centre Schr?dinger equation for Coulomb plus linear potential. The binding energy of the light quark as a function of the distance between heavy quarks is found. Received: 16 January 2002 / Accepted: 7 February 2002     

Low energy antiproton-proton annihilation and meson spectroscopy

Recent results in antiproton-proton annihilation at rest from the Crystal Barrel at CERN/LEAR are reviewed. Rates for annihilation at rest into various two-body channels have been measured. In spite of the complexity of the annihilation mechanism, simple tests based on the underlying quark constituents can be applied. The annihilation process is also useful to investigate the spectrum of light quark mesons and to search for exotic (non-q¯q) mesons. Three scalar states have been found in the 1500 MeV mass region. One of them is a good candidate for the ground state glueball.