Quarkonium annihilation rates

Recent measurements of ratios of quarkonium annihilation rates are used to evaluate the strong fine-structure constant αₛ. Expressions are presented for QCD radiative corrections with αₛ referred to the quark-mass scale. We find αₛ(mb)=0.179_-0.008+0.009 from the ratio {Γ}({Υ}{→}{γ}gg)/ {Γ}({Υ}{→}ggg). The corresponding range of Λ_MS⁽⁴⁾ (the QCD scale factor for four light-quark flavors) is 146--210 MeV, where MS{} denotes the modified-minimal-subtraction scheme. The experimentally more precise but theoretically more questionable ratio of the gluonic and muonic widths of J/{ψ} and {Υ} yields αₛ(mc)=0.29±{}0.02, αₛ(mb)=0.189±{}0.008 when v²/c² corrections to these ratios for J/{ψ} and {Υ} are parametrized linearly. Further predictions are made for ratios of rates.