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arXiv · hep-ex/0302025

Dijet angular distributions in photoproduction of charm at HERA

ZEUS Collaboration
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Abstract

Dijet angular distributions of photoproduction events in which a $D^{*\pm}$ meson is produced in association with one of two energetic jets have been measured with the ZEUS detector at HERA, using an integrated luminosity of 120 pb$^{-1}$. Differential cross sections as a function of the angle between the charm-jet and the proton-beam direction in the dijet rest frame have been measured for samples enriched in direct or resolved photon events. The results are compared with predictions from leading-order parton-shower Monte Carlo models and with next-to-leading-order QCD calculations. The angular distributions show clear evidence for the existence of charm originating from the photon.

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ZEUS Collaboration. 2003-07-10. Dijet angular distributions in photoproduction of charm at HERA. https://doi.org/10.1016/s0370-2693(03)00752-4

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