Experimental limit on ι→γγ and the interpretation of the iota as a glueball

By observing the reaction γγ→Ks0K±π∓, the TPC/Two-Gamma experiment at the SLAC e+e- storage ring PEP has obtained a 95%-confidence-level limit of Γι→γγB(ι→KK¯π)<1.6 keV for the ι(1450) meson. If, as is likely, the ι decays predominantly into KK¯π, the resulting Γι→γγ limit appears to conflict with previous assignments of an observed ργ decay to ι and also with many analyses of η-η’-ι mixing. The contrast of this small γγ width with the large rate for J/ψ→γι is evidence that the ι is a glueball with little admixture of qq¯ states.