Molecular components in J/ψandρ-πpuzzle

Motivated by the large branching fractions of J/ψ→f0(1710)ω/f0(1710)ϕand the light exotic candidates,we found that there may exist molecular states composed of f0(1710)ωand f0(1710)ϕ,which correspond to X(2440)and X(2680)observed a few decades ago.The branching fractions of X(2440)and X(2680)to various PV and KKω(ϕ)channels were estimated in the molecular scenario.In addition,the large branching fractions of J/ψ→f0(1710)ω/f0(1710)ϕindicate sizable molecular components in the J/ψstate.Thus,we consider J/ψas the superposition of thecc¯(1S),f0(1710)ω,and f0(1710)ϕmolecular states.These molecular components have a significant impact on the light hadron decays of J/ψ,which may elucidate the long standingρ−πpuzzle.

Revisiting the determining fraction of glueball component in f_(0) mesons via radiative decays of J/ψ

QCD theory predicts the existence of glueballs,but so far all experimental endeavors have failed to identify any such states.To remedy this discrepancy between QCD,which has proven to be a successful theory for strong interactions,and the failure of experimental searches for glueballs,one is tempted to accept the promising interpretation that the glueballs mix with regular qq states of the same quantum numbers.The lattice estimate of the masses of pure 0++ glueballs ranges from 1 to 2 GeV,which is the region of the f_(0)family.Thus many authors suggest that the f_(0) mesonic series is an ideal place to study possible mixtures of glueballs and qq.In this paper,following the strategy proposed by Close,Farrar and Li,we try to determine the fraction of glueball components inf_(0)mesons using the measured mass spectra and the branching ratios of J/ψ radiative decays intof_(0)mesons.Since the pioneering papers by Close et al.,more than 20 years have elapsed and more accurate measurements have been done by several experimental collaborations,so it is time to revisit this interesting topic using new data.We suppose f_(0)(500)and f_(0)(980)to be pure quark states,while for f_(0)(1370),f_(0)(1500)and f_(0)(1710),to fit both the experimental data of J/ψradiative decay and their mass spectra,glueball components are needed.Moreover,the mass of the pure 0++ glueball is phenomenologically determined.