Differential inclusive-jet cross sections have been measured for different jet radii in neutral current deep inelastic ep scattering for boson virtualities Q^2 > 125 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of 81.7 pb^-1. Jets were identified in the Breit frame using the k_T cluster algorithm in the longitudinally inclusive mode for different values of the jet radius R. Differential cross sections are presented as functions of Q^2 and the jet transverse energy, E_T,B^jet. The dependence on R of the inclusive-jet cross section has been measured for Q^2 > 125 and 500 GeV^2 and found to be linear with R in the range studied. Next-to-leading-order QCD calculations give a good description of the measurements for 0.5 <= R <= 1. A value of alpha_s(M_Z) has been extracted from the measurements of the inclusive-jet cross-section dsigma/dQ^2 with R=1 for Q^2 > 500 GeV^2: alpha_s(M_Z) = 0.1207 +-0.
AbstractDifferential inclusive-jet cross sections have been measured for different jet radii in neutral current deep inelastic ep scattering for boson virtualities Q 2 > 125 GeV 2 with the ZEUS detector at HERA using an integrated luminosity of 81.7 pb −1 . Jets were identified in the Breit frame using the k T cluster algorithm in the longitudinally inclusive mode for different values of the jet radius R. Differential cross sections are presented as functions of Q 2 and the jet transverse energy, E jet T ,B . The dependence on R of the inclusive-jet cross section has been measured for Q 2 > 125 and 500 GeV 2 and found to be linear with R in the range studied. Next-to-leading-order QCD calculations give a good description of the measurements for 0.5 R 1. A value of α s (M Z ) has been extracted from the measurements of the inclusive-jet cross section dσ/dQ 2 with R = 1 for Q 2 > 500 GeV 2 : α s (M Z ) = 0.1207 ± 0.0014(stat.) +0.0035 −0.0033 (exp.) +0.0022 −0.0023 (th.). The variation of α s with E jet T ,B is in a good agreement with the running of α s as predicted by QCD.