Di-Jet production in photon-photon collisions at

Abstract

Di-jet production is studied in collisions of quasi-real photons radiated by the LEP beams at e + e centre-of-mass energies p s ee = 161 and 172 GeV. The jets are reconstructed using a cone jet nding algorithm. The angular distributions of direct and double-resolved processes are measured and compared to the predictions of leading order and next-to-leading order perturbative QCD. The jet energy pro les are also studied. The inclusive two-jet cross-section is measured as a function of E jet T and j jet j and compared to next-to-leading order perturbative QCD calculations. The inclusive t w o-jet cross-section as a function of j jet j is compared to the prediction of the leading order Monte Carlo generators PYTHIA and PHOJET. The Monte Carlo predictions are calculated with di erent parametrisations of the parton distributions of the photon. The in uence of the`underlying event' has been studied to reduce the model dependence of the predicted jet cross-sections from the Monte Carlo generators.