Measurement of Alpha(s) From Jet Rates In Deep-inelastic Scattering At Hera

Abstract Jet production in deep inelastic scattering for 120 Q 2 2 has been studied using data from an integrated luminosity of 3.2 pb −1 collected with the ZEUS detector at HERA. Jets are identified with the JADE algorithm. A cut on the angular distribution of parton emission in the γ ∗ - parton centre-of-mass system minimises the experimental and theoretical uncertainties in the determination of the jet rates. The jet rates, when compared to O ( α s 2 ) perturbative QCD calculations, allow a precise determination of α s ( Q ) in three Q 2 -intervals. The values are consistent with a running of ifα s ( Q ), as expected from QCD. Extrapolating to Q = M Z 0 α s ( M Z 0 ) = 0.117 ± 0.005 (stat) −0.005 +0.004 (syst exp ) ± 0.007 (syst theory ).