Three- and four-jet final states have been measured in photoproduction at HERA using the ZEUS detector with an integrated luminosity of 121 pb−1. The results are presented for jets with transverse energy ETjet>6 GeV and pseudorapidity |ηjet|<2.4, in the kinematic region given by the virtuality of the photon Q2<1 GeV2 and the inelasticity 0.2 <= y <= 0.85 and in two mass regions defined as 25 <= Mn <50 GeV and Mnj >= 50 GeV, where Mnj is the invariant mass of the n-jet system. The four-jet photoproduction cross section has been measured for the first time and represents the highest-order process studied at HERA. Both the three- and four-jet cross sections have been compared with leading-logarithmic parton-shower Monte Carlo models, with and without multi-parton interactions. The three-jet cross sections have been compared to an O(a a_s) perturbative QCD calculation.
Three- and four-jet final states in photoproduction at HERA
MONACO, Vincenzo;SACCHI, Roberto;SOLANO, Ada Maria;
2008-01-01
Abstract
Three- and four-jet final states have been measured in photoproduction at HERA using the ZEUS detector with an integrated luminosity of 121 pb−1. The results are presented for jets with transverse energy ETjet>6 GeV and pseudorapidity |ηjet|<2.4, in the kinematic region given by the virtuality of the photon Q2<1 GeV2 and the inelasticity 0.2 <= y <= 0.85 and in two mass regions defined as 25 <= Mn <50 GeV and Mnj >= 50 GeV, where Mnj is the invariant mass of the n-jet system. The four-jet photoproduction cross section has been measured for the first time and represents the highest-order process studied at HERA. Both the three- and four-jet cross sections have been compared with leading-logarithmic parton-shower Monte Carlo models, with and without multi-parton interactions. The three-jet cross sections have been compared to an O(a a_s) perturbative QCD calculation.File | Dimensione | Formato | |
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