Differential cross sections for jet photoproduction in the reaction ep → e jet X have been measured with the ZEUS detector at HERA using 82.2 pb-1 of integrated luminosity. Inclusive jet cross sections are presented as a function of the jet transverse energy, ET jet, for jets with ET jet > 17 GeV and pseudorapidity -1 <ηjet <2.5, in the γp centre-of-mass-energy range 142 < Wγp < 293 GeV. Scaled jet invariant cross sections are presented as a function of the dimensionless variable xT ≡ 2ET jet/Wγp for (Wγp) = 180 and 255 GeV. Next-to-leading-order QCD calculations give a good description of the measured differential cross sections in both magnitude and shape. The ratio of scaled jet invariant cross sections at the two (Wγp) values shows clear non-scaling behaviour. A value for the strong coupling constant of αs(MZ) = 0.1224 ± 0.0001 (stat.)-0.0019 +0.0022(exp.)-0.0042 +0.0054(th.) has been extracted from a QCD analysis of the measured dσ/dET jet. The variation of αs with ET jet is in good agreement with the running of αs as predicted by QCD.

Scaling Violations and Determination of alfa strong from Jet Production in gamma-p Interactions at HERA

DE PASQUALE, Salvatore;
2003

Abstract

Differential cross sections for jet photoproduction in the reaction ep → e jet X have been measured with the ZEUS detector at HERA using 82.2 pb-1 of integrated luminosity. Inclusive jet cross sections are presented as a function of the jet transverse energy, ET jet, for jets with ET jet > 17 GeV and pseudorapidity -1 <ηjet <2.5, in the γp centre-of-mass-energy range 142 < Wγp < 293 GeV. Scaled jet invariant cross sections are presented as a function of the dimensionless variable xT ≡ 2ET jet/Wγp for (Wγp) = 180 and 255 GeV. Next-to-leading-order QCD calculations give a good description of the measured differential cross sections in both magnitude and shape. The ratio of scaled jet invariant cross sections at the two (Wγp) values shows clear non-scaling behaviour. A value for the strong coupling constant of αs(MZ) = 0.1224 ± 0.0001 (stat.)-0.0019 +0.0022(exp.)-0.0042 +0.0054(th.) has been extracted from a QCD analysis of the measured dσ/dET jet. The variation of αs with ET jet is in good agreement with the running of αs as predicted by QCD.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11386/1064665
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