The Study Of Pseudoscalar Glueball In The Lattice QCD

In this thesis,we aim to explore the production rate of the pseudoscalar glueball in J/ψradiative decay by lattice QCD in quenched approximation.Glueball is an important target for experimental search.The search and study of the glueball,on the one hand,is a direct test of QCD,on the other hand,it is closely related to the non-perturbation property of QCD,and is also an important example to understand the non-perturbation property of QCD.In the radiative decay process of J/ψ,a large number of gluons are produced by the annihilation of quark and antiquark,which makes it an ideal place to search for and study glueball.Lattice QCD is a first principle calculation method based on QCD theory.It is a non-perturbation method that starts from the path integral form of QCD,rotates to Euclidean space-time through wick rotation,and calculates by Monte Carlo method.The lattice QCD theory has made much progresses in the study of the properties of glueball,and it predicts that the mass of pseudoscalar glueball is about 2.4-2.6Ge V.Further study of the process of J/ψradiative decay into pseudoscalar glueball will provide important information for understanding and searching for pseudoscalar glueball.In this thesis the calculation is performed on three anisotropic lat-tices with the spatial lattice spacing ranging from 0.222（2）fm to 0.110（1）fm.As a calibration of some systematical uncertainties,we first extract the M1 form factor?V（0）of the process J/ψ→γηcand get the result V?（0）=1.884（23）in the continuum limit,which gives the partial widthΓ（J/ψ→γηc）=2.350（58）ke V.These results are in agreement with that of previous lattice studies.As for the pseudoscalar glueball G0-+,its mass is derived to be 2.395（14）Ge V,and the form factor?V（0）of the process J/ψ→γG0-+is determined to be?V（0）=0.0246（43）after continuum extrapolation.Finally,the production rate of the pseudoscalar glueball is predicted to be 2.31（90）×10^-4,which is much smaller than that of conven-tional light qˉq states.After the subtraction of the phase space factor,the couplings of J/ψXγare similar where X stands forηstates and the pseu-doscalar glueball.Possibly,the UA（1）anomaly plays an important role for the large couplings of gluons to the flavor singletηstates in J/ψradiative decays.