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The strangeonium-like ss^-g hybrids are investigated from lattice QCD in the quenched approximation.In the Coulomb gauge,spatially extended operators are constructed for 1^--and(0,1,2)^-+states with the color octet ss^-component being separated from the chromomagnetic field strength by the spatial distance r,whose matrix elements between the vacuum and the corresponding states are interpreted as Bethe-Salpeter(BS)wave functions.In each of the(1,2)^-+channels,the masses and the BS wave functions are reliably derived.The 1^-+ground state mass is approximately 2.1-2.2 GeV,and that of 2^-+is approximately 2.3-2.4 GeV,whereas the mass of the first excited state is approximately 1.4 GeV higher.This mass splitting is much larger compared to that expected based on the phenomenological flux-tube model or constituent gluon model for hybrids,which is usually a few hundred MeV.The BS wave functions with respect to r exhibit clear radial nodal structures of a non-relativistic two-body system,which imply that r is a meaningful dynamical variable for these hybrids and motivate a color halo picture of hybrids,in which the color octet ss^-is surrounded by gluonic degrees of freedom.In the 1^--channel,the properties of the lowest two states are consistent with those ofФ(1020)andФ(1680).We did not obtain convincing information with respect toФ(2170).However,we argue that regardless of whetherФ(2170)is a conventional ss^-meson or a ss^-g hybrid in the color halo scenario,the ratio of partial decay widthsΓ(Фη)andΓ(Фη')observed by BESIII can be understood based on the mechanism of hadronic transition of a strangeonium-like meson in addition toη-η'mixing.  相似文献   
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1.格点量子色动力学概述经过多年努力,人们已经成功地将自然界四种基本相互作用(强、弱、电磁、引力)中的前三种统一在量子场论的框架之中,即粒子物理的标准模型(Standard Model,SM)。  相似文献   
3.
阐述了北京谱仪(BES)中KS^0、∧衰变顶点(次级顶点)寻找、径迹参数确定及误差矩阵修正程序的原理。采用BES-Ⅱ的dE/dx和多重库仑散射修正,并考虑谱仪内磁场并非常数而是位置的函数等因素,对用于BES-I的寻找次级顶点的程序进行了修改,使之能应用于BES-Ⅱ的数据处理。进而,通过对北京谱仪J/φ衰变道的蒙特卡罗模拟和数据分析结果,验证了程序的可靠性。  相似文献   
4.
阐述了北京谱仪(BES)中K0S、Λ衰变顶点(次级顶点)寻找、径迹参数确定及误差矩阵修正程序的原理.采用BES-Ⅱ的dE/dx和多重库仑散射修正,并考虑谱仪内磁场并非常数而是位置的函数等因素,对用于BES-Ⅰ的寻找次级顶点的程序进行了修改,使之能应用于BES-Ⅱ的数据处理. 进而,通过对北京谱仪J/ψ衰变道的蒙特卡罗模拟和数据分析结果,验证了程序的可靠性.  相似文献   
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The lowest-lying glueballs are investigated in lattice QCD using N_f = 2 clover Wilson fermions on anisotropic lattices. We simulate at two different and relatively heavy quark masses, corresponding to physical pion masses of mπ~938 MeV and 650 MeV. The quark mass dependence of the glueball masses has not been investigated in the present study. Only the gluonic operators built from Wilson loops are utilized in calculating the corresponding correlation functions. In the tensor channel, we obtain the ground state mass to be 2.363(39) GeV and 2.384(67)GeV at mπ~938 MeV and 650 MeV, respectively. In the pseudoscalar channel, when using the gluonic operator whose continuum limit has the form of ∈_ijkTrB_iD_jB_k, we obtain the ground state mass to be 2.573(55) GeV and 2.585(65) GeV at the two pion masses. These results are compatible with the corresponding results in the quenched approximation. In contrast, if we use the topological charge density as field operators for the pseudoscalar, the masses of the lowest state are much lighter(around 1 GeV) and compatible with the expected masses of the flavor singlet qq meson. This indicates that the operator ∈ijk TrBiDjBk and the topological charge density couple rather differently to the glueball states and qq mesons. The observation of the light flavor singlet pseudoscalar meson can be viewed as the manifestation of effects of dynamical quarks. In the scalar channel, the ground state masses extracted from the correlation functions of gluonic operators are determined to be around 1.4-1.5 GeV, which is close to the ground state masses from the correlation functions of the quark bilinear operators. In all cases, the mixing between glueballs and conventional mesons remains to be further clarified in the future.  相似文献   
6.
在假定有质量的组分胶子是介子的构成子之一的基础上, 根据 Lorentz 群与 S U( Nc) 色群的分析,构造了基态 J P= 1- 介子的波函数, 分析了基态1- 介子中 ρ±、κ±、ρ0 、ω和 ф介子的磁矩与自旋结构(即夸克、反夸克与组分胶子对介子自旋的贡献).得到了关于 ρ±、κ± 介子的磁矩和自旋朗德因子gs 的限制条件以及关于基态1- 介子各组成子(夸克、反夸克或组分胶子)所携带的介子自旋的份额r 的限制条件, 并发现胶子对介子自旋的贡献一般是不可忽略的  相似文献   
7.
阐述了北京谱仪 (BES)中 K0S、Λ衰变顶点 (次级顶点 )寻找、径迹参数确定及误差矩阵修正程序的原理 .采用 BES- 的 d E/ dx和多重库仑散射修正 ,并考虑谱仪内磁场并非常数而是位置的函数等因素 ,对用于BES- 的寻找次级顶点的程序进行了修改 ,使之能应用于 BES- 的数据处理 .进而 ,通过对北京谱仪 J/ψ衰变道的蒙特卡罗模拟和数据分析结果 ,验证了程序的可靠性  相似文献   
8.
We propose a strategy to access the qq component of the p resonance in lattice QCD. Through a mixed action formalism(overlap valence on domain wall sea), the energy of the qq component is derived at different valence quark masses, and shows a linear dependence on m_π~2. The slope is determined to be c_1 =0.505(3)GeV~(-1), from which the valence πρ sigma term is extracted to be σ_(πρ)~(val)= 9.82(6) MeV using the Feynman-Hellman theorem. At the physical pion mass, the mass of the qq component is interpolated to be m_ρ = 775.9±6.0±1.8 MeV, which is close to the p resonance mass. We also obtain the leptonic decay constant of the qq component to be f_ρ-=208.5±5.5±0.9 MeV, which can be compared with the experimental value f_ρ~(exp)≈221 MeV through the relation f_ρ~(exp)=(1/2)Zf_ρ±, with Z_ρ≈1.13 being the on-shell wavefunction renormalization of p owing to the ρ-π interaction. We emphasize that m_ρand f_ρ of the qq component, which are obtained for the first time from QCD, can be taken as the input parameters of p in effective field theory studies where p acts as a fundamental degree of freedom.  相似文献   
9.
We investigate the behavior of the chiral condensate in lattice QCD at finite temperature and finite chemical potential. The study was done using two flavors of light quarks and with a series of β and ma at the lattice size 24×122×6. The calculation was done in the Taylor expansion formalism. We are able to calculate the first and second order derivatives of <ψψ> in both isoscalar and isovector channels. With the first derivatives being small, we find that the second derivatives are sizable close to the phase transition and that the magnitude of ψψ decreases under the influence of finite chemical potential in both channels.  相似文献   
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