ϒ(9.46) decays do test QCD

Abstract QCD makes precise predictions for massive quarkonium decays, Q Q → 3G → 3 jets . The only experimental comparisons so far are for ϒ(9.46) decays into hadrons. However, ϒ(9.46) is not very massive, and three-jet structure is hidden. Despite this we show that ϒ decays can be used to make firm statements about gluon color and spin . They form a nontrivial test of QCD. Simple alternative models with colorless or scalar gluons fail to explain the data.