Bonn 2001 – scientific programme
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T: Teilchenphysik
T 403: QCD 4
T 403.4: Talk
Wednesday, March 28, 2001, 14:45–15:00, HS XII
Inclusive jet cross sections in neutral current DIS — •Oscar González — DESY (ZEUS Coll,Madrid University), Notkestr. 85, 22603 Hamburg, Tel:+49-40-8998-3218
Inclusive production of jets has been studied in neutral-current deep inelastic ep scattering using the ZEUS detector at HERA. Jets have been identified using the longitudinally invariant kT-cluster algorithm in the Breit frame for events with Q2 > 125 GeV2. Differential cross sections have been measured for jets with transverse energy ET,jet > 8 GeV and jet pseudorapidity in the range −2.<ηjet<1.8. These jet variables are defined in the Breit frame and no additional cut in other frames has been required. Measurements of differential cross sections are presented as functions of ET,jet, ηjet and Q2. Next-to-leading-order (NLO) QCD calculations have been compared with the measurements and a good agreement has been obtained at high Q2 or high ET,jet. The azimuthal distribution of the jets in the Breit frame has been measured and found to be non-uniform. NLO QCD describes well the measured asymmetry. This result is the first observation of the azimuthal asymmetry using jets and provides a stringent confirmation for the validity of QCD.