Recent measurements of ratios of quarkonium annihilation rates are used to evaluate the strong fine-structure constant a,. Expressions are presented for QCD radiative corrections with a, referred to the quark-mass scale. We find a , ( m b ) = 0 . 1 7 9 2~~~ from the ratio r(Y-ygg)/ r(Y-ggg). The corresponding range of A& (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 / I~ and Y yields a , ( m , )=0.29+0.02, a , ( m b )=0.189+0.008 when v2/c2 corrections to these ratios for J / $ and Y are parametrized linearly. Further predictions are made for ratios of rates.

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