摘要
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.
作者
Yunheng Ma
Ying Chen
Ming Gong
Zhaofeng Liu
马运恒;陈莹;宫明;刘朝峰(Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;School of Physics,University of Chinese Academy of Sciences,Beijing 100049,China)
基金
Supported by the National Key Research and Development Program of China(2017YFB0203202)
the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDC01040100,XDB34030302)
the support of the National Science Foundation of China(NSFC)(11935017,11775229,11575196,11575197,11621131001)(CRC 110 by DFG and NSFC)
supported by the CAS Center for Excellence in Particle Physics(CCEPP)。
