Radiative decay of ψ(2S) into two pseudo-scalar mesons

Abstract

The existence of pure gluon bound states, the glueballs, is predicted by the Standard Model and several candidate of glueball states have been pursued for years in pp and pp central production on fix-target experiments. and in J/ψ radiative decay on e+e- collision experiments. This dissertation presents a study of the radiative decay of the radially excited counterpart of the J/ψ. the ψ(2S). into two pseudoscalar mesons pairs, i.e. π π. KK and ηη. The ~ 3.79 x 106 ψ(2S) data sample we used for this analysis was collected by a e+e- collision experiment at the Beijing Electron-Position Collider with the Beijing Spectrometer. We give the first measurement of the decay branching fractions of ψ(2S) → γƒ2(1270). ψ(2S) → γƒJ(1710) → γKK.ψ(2S) → γƒJ(1710) → γπ+π- and ψ(2S) → γƒ12(1525). These results agree with the predicted "15% rule", when compared with the corresponding J/ψ decay branching fractions. The spin-parity of the glueball candidate ƒJ(1710) is yet to be determined. The Xc0 and Xc2 decay into π0π0 and ηη branching fractions have also been measured with a pattern that follows the SU(3) flavor symmetry.