Professor Amanda Cooper-Sarkar

Abstract:

Charged particle production has been measured in deep inelastic scattering (DIS) events over a large range of x and Q² using the ZEUS detector. The evolution of the scaled momentum, xp, with Q², in the range 10 to 1280 GeV², has been investigated in the current fragmentation region of the Breit frame. The results show clear evidence, in a single experiment, for scaling violations in scaled momenta as a function of Q². © 1997 Elsevier Science B.V.

Abstract:

Events containing an isolated prompt photon with high transverse energy, together with a balancing jet, have been observed for the first time in photoproduction at HERA. The data were taken with the ZEUS detector, in a γp centre of mass energy range 120-250 GeV. The fraction of the incoming photon energy participating in the production of the prompt photon and the jet, xγ, shows a strong peak near unity, consistent with LO QCD Monte Carlo predictions. In the transverse energy and pseudorapidity range 5 ≤ E^γ T < 10 GeV, -0.7 ≤ η^γ < 0.8, E^jet T ≥ 5 GeV, and -1.5 ≤ η^jet ≤ 1.8, with x^OBS γ > 0.8, the measured cross section is 15.3 ± 3.8 ± 1.8 pb, in good agreement with a recent NLO calculation. © 1997 Elsevier Science B.V.