0++三胶子标胶球与QCD求和规则

计算了0⁺⁺三胶子标量流的两点函数,其中计及了直至量纲为6的凝聚项的贡献.在＂零宽度共振态加连续谱＂的谱函数模型中,得到了0⁺⁺三胶子标胶球的量子色动力学求和规则,由此定出了该标胶球的质量.     

QCD求和规则与强子物理

量子色动力学（QCD）求和规则是强子物理研究中的一种重要的非微扰方法, 已经成为强子物理与核物理研究中有力的工具。 简单介绍了QCD求和规则的基本概念、 方法与应用, 特别讨论了QCD求和规则近年来的发展和与之相关的一些前沿问题。 QCD sum rule is an important nonperturbative method in hadron physics, it has been a powerful technique in study of hadron physics and nuclear physics.We give a brief introduction to the basic idea, the method and its application of QCD sum rule, emphasize the development of this method and some topics in recent years.     

有限温度QCD求和规则与ρ介子

计算了三胶子凝聚对ρ介子在有限温度下的QCD求和规则的贡献,进而在弦模型中研究了ρ介子的特性对温度的依赖性.结果表明:如果各凝聚具有相同的临界温度,则在我们所考虑的低温范围内,表征ρ介子特性的一些参量当温度接近临界温度时(即120—200MeV之间)变化显簇.     

用改进的格点哈密顿量计算2+1维QCD0++胶球质量

用改进的格点哈密顿量和截断本征方程法计算2+1维QCD 0⁺⁺胶球质量,结果显示较好的标度行为.     

QCD求和规则的张量胶子球(2++)的质量

利用量子色动力学求和规则计算了张量胶子球 (2++ )的质量 ,其结果与北京正负电子对撞机的BES实验组和MARKIII实验组的测量结果一致 ,表明张量胶子球的质量约 2 .2 3GeV左右。The mass of the tensor glueball (2 ++ ) is calculated in quantum chromodynamics(QCD) spectral sum rules. The theoretical prediction is in good agreement with the measurements of BES collaboration at BEPC, Beijing and MARK III, which indicates that the mass of the tensor glueball may be around 2.23 GeV.     

G(1590)作为0++胶子球候选者的一个直接的检验

本文用推广的矩分析法^[1]研究了在～17GeV处J/ψ辐射衰变产生的宽共振峰的结构,提供了一个检测是否此峰中可能同时存在θf₂(1720)和G(1590)态的方法.如果G(1590)确实存在,则是对G(1590)作为胶子球候选者的一个直接的检验.     

混合效应在QCD求和规则下对标量胶球质量的影响

在QCD求和规则的框架下考虑了纯胶球和普通介子态的混合效应对二者质量的影响.在关联函数的构造中,胶子流和夸克流都被认为既和胶球态有耦合,也和夸克态有耦合.利用QCD低能定理,构造了一个混合关联函数.通过这些关系及两共振态近似,得出了0⁺⁺胶球和夸克态的质量,它们与各自的纯态的质量相差不大.     

非因子化方法研究D+→K0K+衰变

在领头阶和αs 修正阶,用QCD因子化方法,并对它的软胶子效应用光锥QCD求和规则分析D⁺→K⁰K⁺衰变过程,我们分析发现朴素因子化方法的结果远离实验结果,QCD因子化方法结果靠近实验结果,但是,在QCD因子化方法中,若考虑软胶子效应,其结果与实验结果相一致.另外,计算发现,软胶子效应在该衰变道中有相当大的贡献,因此不能被忽略     

3+1维格点规范理论0++和0－－胶球质量

在哈密顿形式下,把无规相近似方法从(2+1)维SU(2)格点规范场推广到3+1维SU(3)格点规范场,利用这种改进的耦合集团展开方法计算3+1维SU(3)的真空波函数和0^－－与0⁺⁺胶球质量之比,得到令人满意的结果:γ=m(0－－)m(0++)=1.8578±0.0506.     

(2+1)维SU(3)0++胶球波函数

采用截断本征方程的方法,选择连接图作为独立图,计算(2+1)维SU(3)胶球波函数,其μ0F和μ2F表现出较好的标度行为.     

Fermion Corrections to Mass of Scalar Glueball in QCD Sum Rule

Contributions of fermions to the mass of the scalar glueball 0^＋＋ are calculated at two-loop level in the framework of QCD sum rules. It slightly changes the coefficients in the operator product expansion （OPE） and shifts the mass of glueball to 1.72 ± 0.07 GeV.     

Fermion Corrections to Mass of Scalar Glueball in QCD Sum Rule

Contributions of fermions to the mass of the scalar glueball 0⁺⁺ are calculated at two-loop level in the framework of QCD sum rules. It slightly changes the coefficients in the operator product expansion (OPE) and shifts the mass of glueball to 1.72 ±0.07 GeV.     

对北京谱仪上新观测态的一个理论解释

最近, 北京谱仪在J/ψ的辐射衰变中发现, 在正反质子的阈附近有反常增强, 即可能存在共振态X(1860)和X(1835). 针对这一发现, 提出了新粒子的三胶子胶球态解释方案, 并且应用QCD求和规则计算了此胶球态的质量. 考虑到理论上的不确定因素, 计算结果表明该胶球态的质量峰位于1.9GeV到2.7GeV之间. 事实上, 北京谱仪发现的新共振态的确表现出了一些三胶子态的行为. 结论是, 此新粒子很有可能是重子偶素和胶球态的混合态.     

Existence of Tensor Glueball ξ(2230) and Its Mass, Spin, and Decay Width

In order to solve the current experimental controversy on the existence of the tensor glueball ξ(2230), we examine whether the conclusion from Seth's experimental measurement, which rejects existence of ξ(2230), is reliable. We claim that the non-observation of the resonance structure by Seth is not a sound ground for rejecting the existence of ξ(2230) but it may just indicate that ξ(2230) has a broad width. We also study the tensor glueball properties: the mass, spin, and decay width. Our theoretical predictions of the mass and the spin of the ξ(2230) using QCD sum rule are about 2.23 GeV and J=2, respectively. Our theoretical results also evidently show that the ξ(2230) must have a total decay width of about 100 MeV, which is much broader than the reported 20 MeV but a small partial decay width of 2 MeV into pp decay channel.     

Reanalyzing Pentaquark Θ+(1540) in Framework of QCD Sum Rules Approach with Direct Instantons

In this article, we study the pentaquark state Θ⁺(1540) with a (scalar) diquark-(pseudoscalar) diquark-antiquark type interpolating current in the framework of the QCD sum rules approach by including the contributions from the direct instantons. The numerical results indicate that the contributions from the direct instantons are very small and can be safely neglected.     

QCD sum rule study of the masses of light tetraquark scalar mesons

We study the low-lying scalar mesons of light u, d, s flavors in the QCD sum rule. Having all possible combinations of tetraquark currents in the local form, QCD sum rule analysis has been carefully performed. We found that using the appropriate tetraquark currents, the masses of σ, κ, f₀ and a₀ mesons appear in the region of 0.6–1 GeV with the expected ordering. The results are compared with that of the conventional currents, where the masses are considerably larger.     

QCD Sum Rule Study of π_1S States

We study the states π_1 (1600) and π_1 (2015) in the QCD sum rule.We classify the tetraquark currents of the quantum numbers I~GJ~(PC)=1~-1~(-+),and find that the flavor structure (3 (×) -6)(+) (6(×)3) is preferred when using a diquark-antidiquark construction.By using both the SVZ and finite energy sum rules,we obtain a mass around 1.6 and 2.0 GeV,for the states with the quark contents qqqq and qsqs,respectively.We also study their decay patterns.     

A Lattice Study of the Glueball Spectrum

Glueball Spectrum is studied using an improved gluonic action on asymmetric lattices in the pure SU(3) gauge theory.The smallest spatial lattice spacing is about 0.08 fm which makes the extrapolation to the continuum limit more reliable.In particular.attention is paid to the scalar glueball mass which is known to have problems in the extrapolation.Converting our lattice results to physical units using the scale set by the static quark potential,we obtain the following results for the glueball masses:MG(0 )=1730(90)MeV for the scalar glueball mass and MG(2 )=2400(95)MeV for the tensor glueball.     

P-wave ?b states: masses and pole residues

In this study, we consider all P-wave begin{document}$Omega_{b}$end{document} states represented by interpolating currents with a derivative and calculate the corresponding masses and pole residues using the QCD sum rule method. Because of the large uncertainties in our calculation compared with the small difference in the masses of the excited begin{document}$Omega_{b}$end{document} states observed by the LHCb collaboration, it is necessary to study other properties of the P-wave begin{document}$Omega_{b}$end{document} states represented by the interpolating currents investigated in the present work to gain a better understanding of the four excited begin{document}$Omega_{b}$end{document} states observed by the LHCb collaboration.     

Glueballs and Instantons in Lattice SU(2) Gauge Theory

The SU(2) glueball masses and the gluonic correlation functions in the J^P = 0⁺,2⁺ and 0^- channels are calculated from the cooled and uncooled gauge configurations. The improved action and the anisotropic lattice are used in this work. The instanton-induced attractive force in the 0⁺ channel and the repulsive force in the 0^- channel are confirmed by the Monte Carlo simulation. There is evidence that the instanton vacuum contribution to the 0⁺ glueball mass is significant.