Search

Abstract: Differential cross sections for dijet photoproduction and this process in association with a leading neutron, , have been measured with the ZEUS detector at HERA using an integrated luminosity of 40 pb−1. The fraction of dijet events with a leading neutron was studied as a function of different jet and event variables. Single- and double-differential cross sections are presented as a function of the longitudinal fraction of the proton momentum carried by the leading neutron, , and of its transverse momentum squared, . The dijet data are compared to inclusive DIS and photoproduction results; they are all consistent with a simple pion-exchange model. The neutron yield as a function of was found to depend only on the fraction of the proton beam energy going into the forward region, independent of the hard process. No firm conclusion can be drawn on the presence of rescattering effects. [Copyright &y& Elsevier]

Abstract: Inclusive-jet and dijet differential cross sections have been measured in neutral current deep inelastic ep scattering for exchanged boson virtualities with the ZEUS detector at HERA using an integrated luminosity of 82 pb−1. Jets were identified in the Breit frame using the cluster algorithm. Jet cross sections are presented as functions of several kinematic and jet variables. The results are also presented in different regions of . Next-to-leading-order QCD calculations describe the measurements well. Regions of phase space where the theoretical uncertainties are small have been identified. Measurements in these regions have the potential to constrain the gluon density in the proton when used as inputs to global fits of the proton parton distribution functions. [Copyright &y& Elsevier]