Études Francaises

A measurement of the proton structure function F 2 (x,Q 2 ) is presented in the kinematic range 0.045 GeV 2 <Q 2 <0.65 GeV 2 and 6·10 −7 <x<1·10 −3 . The results were obtained using a data sample corresponding to an integrated ...

This paper reports the cross section measurements for the process ep → e J/ψ p for Q 2 < 4 GeV 2 at GeV, based on an integrated luminosity of about 0.5 pb −1 , using the ZEUS detector. The J/ψ was detected in its e + e − and μ + μ − decay modes. The photoproduction cross ...

Dijet production by almost real photons has been studied at HERA with the ZEUS detector. Jets have been identified using the cone algorithm. A cut on x γ OBS , the fraction of the photon energy participating in the production of the two jets of highest transverse energy, is used to ...

Measurements of the cross sections for charged current deep inelastic scattering in e − p collisions with longitudinally polarised electron beams are presented. The measurements are based on a data sample with an integrated luminosity of 175 pb−1 collected with the ZEUS detector at HERA at a centre-of-mass energy of 318 GeV. The total cross section is given for positively and negatively polarised electron beams. The differential cross-sections d σ/dQ 2, d σ/dx and d σ/dy are presented for Q 2>200 GeV2. The double-differential cross-section d 2 σ/dxdQ 2 is presented in the kinematic range 280Q 22 and 0.015x

The production of φ mesons in the reaction e + p → e + φp (φ → K + K − ), for and virtual photon-proton centre of mass energies (W) in the range 42–134 GeV, has been studied with the ZEUS detector at HERA. When compared to lower energy data at similar 2 , the ...

In deep inelastic neutral current scattering of positrons and protons at the center of mass energy of 300 GeV, we observe, with the ZEUS detector, events with a high energy neutron produced at very small scattering angles with respect to the proton direction. The events constitute a fixed fraction of the deep inelastic, neutral current event sample independent of Bjorken x and Q 2 in the range 3 • 10 −4 < x BJ < 6 • 10 −3 and 10 < Q 2 < 100 GeV 2 .