Determining the gluonic content of isoscalar mesons

Abstract

We develop tools to determine the gluonic content of a resonance of known mass, width and J P C from its branching fraction in radiative quarkonium decays and production cross section in γγ collisions. We test the procedures by applying them to known qq mesons, then analyze four leading glueball candidates. We identify inconsistencies in data for J/ψ → γf 0 (1500) and J/ψ → γf J (1710) whose resolution can quantify their glueball status.When Γ(f 0 (1500) → γγ) and Γ(f J (1710) → γγ) are known, the nn, ss, gg mixing angles can be determined. The enigmatic situation in 1400-1500 MeV region of the isosinglet 0 −+ sector is discussed.1

X(1835) as the lowest mass pseudoscalar glueball and proton spin problem

“…But, this identification is doubted by large disagreement between its experimental observation and theoretical predictions of both lattice QCD [15] and QCD sum rules calculation [16,17], of which values range between m = 1.86 and 2.7 GeV. Furthermore, the peculiarities of η(1440) production in different reactions support these doubts on its glueball origin [20,21]. Recently, BES Collaboration observed X(1835) state in the reactions J/Ψ → γpp and J/Ψ → γη ′ π + π − [7,8].…”

Observation of pseudoscalar and tensor resonances inJ/ψ→γϕϕ

“…The glueball spectrum has been predicted by Lattice QCD [4][5][6], where the lowest-lying glueballs are scalar (mass 1.5−1.7 GeV/c 2 ), tensor (mass 2.3−2.4 GeV/c 2 ), and pseudoscalar (mass 2.3−2.6 GeV/c 2 ). Radiative decays of the J/ψ meson provide a gluon rich environment and are therefore regarded as one of the most promising hunting grounds for glueballs [7,8].…”

The lightest scalar glueball

“…In the following papers [13,20,21,22,23], several schemes have been suggested for the mixing of the lightest scalar glueball with the neighbouring qq-states. However, all these schemes did not take account of special features of the mixing which are due to the transition of a resonance into real mesons, although just these transitions, as was shown in a specified K-matrix analysis, determine the structure of the 00 ++ -wave around 1500 MeV.…”