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T: Fachverband Teilchenphysik

T 26: QCD 2

T 26.3: Talk

Tuesday, February 28, 2012, 17:25–17:40, ZHG 009

Inclusive-jet photoproduction at HERA — •Denys Lontkovskyi — Notkestrasse 85, DESY, Hamburg, Germany

The study of jet production at ep collider HERA has been well established as a way of testing perturbative QCD. Jet cross sections allow to test theory predictions, extract the fundamental parameter of the theory, α_s, and give a valuable input for QCD fits in order to determine the parton distribution functions of the proton. Inclusive-jet cross sections were measured in ep → e + jet + X for photon virtuality Q² < 1 GeV² and γ p centre-of-mass energies in range 142 < W_{γ p} < 293 GeV with the ZEUS detector using an integrated luminosity of 300 pb⁻¹. Single-differential cross sections are presented as functions of the jet transverse energy, E_T^jet, and pseudorapidity, η^jet, for jets with E_T^jet>17 GeV and −1<η^jet<2.5. In addition, measurements of double-differential inclusive-jet cross sections are presented as functions of E_T^jet in different regions of η^jet. Next-to-leading-order QCD predictions are compared to the measurements, and give a good description of the measured cross sections except at high η^jet. Precise values of α_s(M_Z) were extracted from the measurements and the energy-scale dependence of the coupling was determined.