Recent photoproduction results from ZEUS

Recent results for inclusive jet cross sections, dijet cross sections and dijet angular distributions are compared with NLO perturbative QCD calculations. The observation of isolated high PT photons (prompt photons) is also reported

F-2(D(3)) measurements at ZEUS

Results on the diffractive structure function F-2(D(3)) in deep inelastic neutral current positron-proton scattering (DIS) have been obtained by the ZEUS collaboration using two different methods. Diffractive interactions are selected by either requiring a small, not exponentially suppressed invariant hadronic mass M-X in the main detector or by detecting a fast proton in the ZEUS leading proton spectrometer (LPS). The results of the two methods are compared

Event shape analysis of multihadronic final states in deep inelastic rapidity gap events at HERA

A global event shape analysis of the multihadronic final states observed in deep inelastic scattering (DIS) with a large forward rapidity gap (LRG) is performed in the range Q(2) greater than or equal to 5 GeV2, 160 GeV less than or equal to W less than or equal to 250 GeV and eta(max) less than or equal to 1.8. Particular emphasis is paid to the dependence of these variables, measured in the gamma*-pomeron rest frame, upon M-X, the mass of the hadronic final state. With increasing M-X the multihadronic final states become planar. The broadening effects exhibited by the data can be described by including a gluon density in models where the pomeron has a partonic structure or alternatively by considering a direct coupling of the pomeron to quark and gluon pairs

Leading baryons at low x(L) in DIS and photoproduction at ZEUS

Results obtained by the ZEUS collaboration on leading baryon production in the proton fragmentation region are presented. The reaction gamma p --> NX, with N a proton or a neutron, is examined both at low and high photon virtuality

Fragmentation functions at ZEUS

The scaled momentum spectra of final state charged hadrons produced in Deep Inelastic Scattering in the ranges 10 < Q(2) < 1280 GeV2 and 6 . 10(-4) < x(Bjorken) < 5 . 10(-2) have been measured in the current region of the Breit frame using the ZEUS detector. The evolution with Q(2) of the scaled momentum, x(p) = 2p(Breit)/Q, has been investigated and preliminary results are presented which show evidence for scaling violations and support for the universality of quark fragmentation

Jet shapes at HERA

The shape of jets produced in quasi-real photon-proton interactions and deep inelastic positron-proton scattering (DIS) at high Q(2) (Q(2) > 100 GeV2) has been measured with the ZEUS detector at HERA. Jets with transverse energies E-T(jet) > 14 GeV and pseudorapidities (eta(jet)) in the range -1 collisions, and are similar to those in e(+)e(-) interactions

Measurement of dijets in DIS and comparison to NLO calculations

We report a measurement of the dijet production cross section in neutral current deep inelastic scattering with the ZEUS detector at the HERA ep collider. Dijet events are identified with the cone algorithm and the results are compared to next-to-leading order perturbative QCD calculations. The systematic uncertainties of both the measurement and the calculation we discussed

Diffractive production of charm and jets at HERA

Measurements are presented of dijet cross sections in diffractive photoproduction and of D*(+/-) production in diffractive deep inelastic scattering at HERA. A combined QCD analysis of the diffractive dijet cross sections and diffractive structure function results leads to a picture in which the pomeron has a substantial gluon component with a hard momentum spectrum