Inclusive jet differential cross sections for the reaction ep → jet + X at Q 2 below 4 GeV 2 have been measured with the ZEUS detector at HERA using an integrated luminosity of 0.55 pb −1 . These cross sections are given in the kinematic region 0.2 < y < 0.85, for jet pseudorapidities in the ep -laboratory range −1 < η jet < 2 and refer to jets at the hadron level with a cone radius of one unit in the η - θ plane. These results correspond to quasi-real photoproduction at centre-of-mass energies in the range 130–270 GeV and, approximately, for jet pseudorapidities in the interval −3 < η jet ( λp CMS) < 0. These measurements cover a new kinematic regime of the partonic structure of the photon, at typical scales up to ∼300 GeV 2 and photon fractional momenta down to x γ ∼ 10 −2 . Leading logarithm parton shower Monte Carlo calculations, which include both resolved and direct processes and use the predictions of currently available parametrisations of the photon parton distributions, describe in general the shape and magnitude of the measured η jet and E t jet distributions.
Second systematic error is uncertainty in the ET scale.
Second systematic error is uncertainty in the ET scale.
Second systematic error is uncertainty in the ET scale.
Photon proton cross sections for elastic light vector meson production, σelνp, inelastic diffractive production, σndνp, non-diffractive production, σdνp, as well as the total cross section, σtotνp, have been measured at an average υp center of mass energy of 180 GeV with the ZEUS detector at HERA. The resulting values are σelνp = 18 ± 7 μb, σdνp = 33 ± 8 μb, σndνp = 91 ± 11 μb, and σtotνp 143 ± 17 μb, where the errors include statistical and systematic errors added in quadrature.
No description provided.
Errors contain both statistics and systematics.
Cross section for the elastic (ie. gamma p --> VM p) cross section.. Errors contain both statistics and systematics.
This is the first full solid angle analysis of large transverse energy events in\(p\bar p\) collisions at the CERN collider. Events with transverse energies in excess of 200 GeV at\(\sqrt s= 630 GeV\) are studied for any non-standard physics and quantitatively compared with expectations from perturbative QCD Monte Carlo models. A corrected differential cross section is presented. A detailed examination is made of jet profiles, event jet multiplicities and the fraction of the transverse energy carried by the two jets with the highest transverse jet energies. There is good agreement with standard theory for events with transverse energies up to the largest observed values\(( \approx \sqrt {s/2} )\) and the analysis shows no evidence for any non-QCD mechanism to account for the event characteristics.
No description provided.
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