A search has been made for lepton-flavor-violating interactions of the type ep → lX, where l denotes a μ or τ with high transverse momentum, at a center-of-mass energy, √ s, of 300GeV with an integrated luminosity of 47.7 pb using the ZEUS detector at HERA. No evidence was found for lepton-flavor violation and constraints were derived on leptoquarks (LQs) that could mediate such interactions. F...

This paper presents the first analysis of diffractive photon dissociation events in deep inelastic positron-proton scattering at HERA in which the proton in the final state is detected and its momentum measured. The events are selected by requiring a scattered proton in the ZEUS leading proton spectrometer (LPS) with xL > 0.97, where xL is the fraction of the incoming proton beam momentum carri...

Multiplicity moments of charged particles in deep inelastic ep scattering have been measured with the ZEUS detector at HERA using an integrated luminosity of 38.4 pb. The moments for Q > 1000 GeV were studied in the current region of the Breit frame. The evolution of the moments was investigated as a function of restricted regions in polar angle and, for the first time, both in the transverse m...

The ep neutral-current deep inelastic scattering differential cross-sections dσ/dQ, for Q > 400 GeV, dσ/dx and dσ/dy, for Q > 400, 2500 and 10000 GeV, have been measured with the ZEUS detector at HERA. The data sample of 47.7 pb was collected at a center-ofmass energy of 300 GeV. The cross-section, dσ/dQ, falls by six orders of magnitude between Q = 400 and 40000 GeV. The predictions of the Sta...

A measurement of the proton structure function F2(x,Q ) is presented in the kinematic range 0.045GeV < Q < 0.65GeV and 6 ·10 < x < 1 ·10. The results were obtained using a data sample corresponding to an integrated luminosity of 3.9 pb in ep reactions recorded with the ZEUS detector at HERA. Information from a silicon-strip tracking detector, installed in front of the small electromagnetic calo...

Inclusive photoproduction of D mesons has been measured for photon-proton centre-of-mass energies in the range 130 < W < 280GeV and photon virtuality Q < 1GeV. The data sample used corresponds to an integrated luminosity of 37 pb. Total and differential cross sections as functions of the D transverse momentum and pseudorapidity are presented in restricted kinematical regions and the data are co...

The inelastic production of J/ψ mesons in ep collisions has been studied with the ZEUS detector at HERA using an integrated luminosity of 109 pb. The J/ψ mesons were identified using the decay channel J/ψ → μμ. The measurements were performed in the kinematic range 2 < Q < 80GeV, 50 < W < 250GeV, 0.2 < z < 0.9 and −1.6 < Ylab < 1.3, where Q is the virtuality of the exchanged photon, W is the ph...

Cross sections for ep charged current deep inelastic scattering at a centreof-mass energy of 318GeV have been determined with an integrated luminosity of 60.9 pb collected with the ZEUS detector at HERA. The differential cross sections dσ/dQ, dσ/dx and dσ/dy for Q > 200GeV are presented. In addition, dσ/dxdQ has been measured in the kinematic range 280GeV < Q < 17 000GeV and 0.008 < x < 0.42. T...

The production of D, D, D, D s and Λ + c charm hadrons and their antiparticles in ep scattering at HERA was measured with the ZEUS detector using an integrated luminosity of 79 pb. The measurement has been performed in the photoproduction regime with the exchanged-photon virtuality Q < 1GeV and for photon-proton centre-of-mass energies in the range 130 < W < 300GeV. The charm hadrons were recon...

This paper presents the first analysis of diffractive photon dissociation events in deep inelastic positron-proton scattering at HERA in which the proton in the final state is detected and its momentum measured. The events are selected by requiring a scattered proton in the ZEUS leading proton spectrometer (LPS) with xL > 0.97, where xL is the fraction of the incoming proton beam momentum carri...