Speaker
Description
Isolated photons with high transverse energy components have been studied in $ep$
scattering with the ZEUS detector at HERA, using 326 pb$^−1$ integrated luminosity. The kinematic region includes photon virtualities 10 < $Q^2$ < 350 GeV$^2$. Photons with transverse energy 4 < $E_T^\gamma$ < 15 GeV and pseudorapidity −0.7 < $\eta^\gamma$ < 0.9 were measured with accompanying jets having transverse energy and pseudo rapidity 2.5 < $E_T^{jet}$ < 35 GeV and −1.5 < $\eta^{jet}$ < 1.8. Differential cross sections are presented for the following variables: the fraction of the incoming photon energy and momentum that is transferred to the photon and the jet, the fraction of proton energy taken by the parton that interacts with the photon, and the azimuthal angle and the pseudorapidity difference between the prompt photon and the jet and between the prompt photon and the scattered electron. Comparisons are made with several different theoretical calculations: a leading-logarithm Monte Carlo simulation, a next-to-leading-order QCD calculation and a calculation using the $k_T$ factorisation approach.
| Experimental Collaboration | ZEUS |
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