Abstract.
Di-jet production is studied in collisions of quasi-real photons at e + e- centre-of-mass energies \(\sqrt{s_{\protect\bf\mathrm{ee}}}\) from 189 to 209 GeV at LEP. The data were collected with the OPAL detector. Jets are reconstructed using an inclusive \(k_{\perp}\)-clustering algorithm for all cross-section measurements presented. A cone jet algorithm is used in addition to study the different structure of the jets resulting from either of the algorithms. The inclusive di-jet cross-section is measured as a function of the mean transverse energy \(\bar{E}^{\mathrm{jet}}_{\mathrm{T}}\) of the two leading jets, and as a function of the estimated fraction of the photon momentum carried by the parton entering the hard sub-process, \(x_{\gamma}\), for different regions of \(\bar{E}^{\mathrm{jet}}_{\mathrm{T}}\). Angular distributions in di-jet events are measured and used to demonstrate the dominance of quark and gluon initiated processes in different regions of phase space. Furthermore the inclusive di-jet cross-section as a function of \(\eta^\mathrm{jet}\) and \(\Delta\eta^\mathrm{jet}\)is presented, where \(\eta^\mathrm{jet}_\mathrm{cntr}\)is the jet pseudo-rapidity. Different regions of the \(x_{\gamma}^ + \)-\(x_{\gamma}^-\)-space are explored to study and control the influence of an underlying event. The results are compared to next-to-leading order perturbative QCD calculations and to the predictions of the leading order Monte Carlo generator PYTHIA.
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Received: 20 December 2002, Published online: 17 October 2003
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The OPAL Collaboration. Di-jet production in photon-photon collisionsat \(\sqrt{s_{\protect\bf\mathrm{ee}}}\) from 189 to 209 GeV. Eur. Phys. J. C 31, 307–325 (2003). https://doi.org/10.1140/epjc/s2003-01360-8
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DOI: https://doi.org/10.1140/epjc/s2003-01360-8