Measurement of ${\alpha }_S$ from Jet Rates in Deep Inelastic Scattering at HERA

Abstract

Jet production in deep inelastic scattering for $120<Q^2<3600$~GeV${}^2$ 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 ${\gamma }^{\ast }$-parton centre-of-mass system minimises the experimental and theoretical uncertainties in the determination of the jet rates. The jet rates, when compared to $\mathcal{O}$(${\alpha }_s$^2$)perturbativeQCDcalculations,allowaprecisedeterminationof$α_{s}(Q)$inthree$Q^2$-intervals.Thevaluesareconsistentwitharunningof$α_{s}(Q)$,asexpectedfromQCD.Extrapolatingto$Q=M_{Z^0}$yields$α_{s}(M_{Z^0}) = 0.117~\pm~0.005~(stat)~^{+0.004}_{-0.005}~(syst_{exp})~ ~{\pm~0.007}~(syst_{theory})$.

22 pages, latex, 4 figures appended as uuencoded file