Leptonic Decay of the (1S) Meson at Third Order in QCD

We present the complete next- to- next- to- next- to- leading order short- distance and bound- state QCD correction to the leptonic decay rate Gamma(gamma(1s) -> l(+) l(-)) of the lowest- lying spin- 1 bottomonium state. The perturbative QCD prediction is compared to the measurement Gamma(Y(1S) -> e(+)e(-)) = 1.340(18) keV.