Experimental limit onι→γγand the interpretation of the iota as a glueball

Abstract

By observing the reaction γγ→$K_s^0$ $K^{\pm }$ ${\pi }^{\mp }$, the TPC/Two-Gamma experiment at the SLAC $e^{+}$ $e^{\mathrm{-}}$ storage ring PEP has obtained a 95%-confidence-level limit of ${\Gamma }_{\iota \to \gamma \gamma }$B(ι→KK¯π)ι(1450) meson. If, as is likely, the ι decays predominantly into KK¯π, the resulting ${\Gamma }_{\iota \to \gamma \gamma }$ 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.