Determining the gluonic content of isoscalar mesons

We develop tools to determine the gluonic content of a resonance of known mass, width, and JPC 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→γf₀(1500) and J/ψ→γfJ(1710) whose resolution can quantify their glueball status. When Γ(f₀(1500)→γγ) and Γ(fJ(1710)→γγ) are known, the nn ̄ \=,ss̄,gg mixing angles can be determined. The enigmatic situation in the 1400--1500 MeV region of the isosinglet 0^-+ sector is discussed.