Professor Amanda Cooper-Sarkar

Abstract:

New ZEUS data are added into the NLO QCD analysis of the ZEUS-JETS PDF fit. The addition of high-Q2 NC and CC e- p inclusive cross-section data improves the determination of the u-valence quark at high x. The addition of high-Q2 CC e+p inclusive cross-section data improves the determination of the d-valence quark at high x. The addition of lower-Q2 NC e+ p inclusive cross-section data, run at three difierent proton beam energies, improves the determination of the sea and gluon PDFs at small x. The new PDF fit is called the ZEUS09 PDF fit.

Abstract:

Deeply virtual Compton scattering, γ*p→γp has been measured in e+p collisions at HERA with the ZEUS detector using an integrated luminosity of 61.1 pb-1. Cross sections are presented as a function of the photon virtuality, Q2, and photon-proton centre-of-mass energy, W, for a wide region of the phase space, Q2 > 1.5GeV2 and 40 < W < 170GeV. A subsample of events in which the scattered proton is measured in the leading proton spectrometer, corresponding to an integrated luminosity of 31.3 pb-1, is used for the first direct measurement of the differential cross section as a function of t, where t is the square of the four-momentum transfer at the proton vertex. © SISSA 2009.