Glueball spectrum from Nf = 2 lattice QCD study on anisotropic latticesThe numerical calculations were carried out on Tianhe-1A at the National Supercomputer Center (NSCC) in Tianjin and the GPU cluster at Hunan Normal University. This work is supported in part by the National Science Foundation of China (NSFC) (11575196, 11575197, 11335001, 11405053, 11405178, 11275169). Y. C., Z. L. and C. L. also acknowledge the support of NSFC (11261130311) (CRC 110 by DFG and NSFC). Y. C. thanks the support by the CAS Center for Excellence in Particle Physics (CCEPP). C.L. is also funded in part by National Basic Research Program of China (973 Program) (2015CB856700). M. G. thanks the support by the Youth Innovation Promotion Association of CAS (2015013)
Wei Sun (Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China, School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China); Long-Cheng Gui (Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha 410081, China, Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Changsha 410081, China); Ying Chen (Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China, School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China); Ming Gong (Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China, School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China); Chuan Liu (School of Physics and Center for High Energy Physics, Peking University, Beijing 100871, China, Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China); et al - Show all 10 authors
The lowest-lying glueballs are investigated in lattice QCD using Nf = 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 εijk TrBiDjBk, 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 meson. This indicates that the operator εijk TrBiDjBk and the topological charge density couple rather differently to the glueball states and 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.
