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Observation of isolated high-E photons in photoproduction at HERA
Journal article   Peer reviewed

Observation of isolated high-E photons in photoproduction at HERA

ZEUS Collaboration, J. Repond and U. Mallik
Physics letters. B, Vol.413(1-2), pp.201-216
11/1997
DOI: 10.1016/S0370-2693(97)01164-7

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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 ≤ ETγ < 10 GeV, −0.7 ≤ ηγ < 0.8, ETjet ≥ 5 GeV, and −1.5 ≤ ηjet ≤ 1.8, with xγOBS > 0.8, the measured cross section is 15.3 ± 3.8 ± 1.8 pb, in good agreement with a recent NLO calculation.

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