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Measurement of azimuthal asymmetries in neutral current deep inelastic scattering at HERA

ZEUS Collaboration
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Abstract

The distribution of the azimuthal angle of charged and neutral hadrons relative to the lepton plane has been studied for neutral current deep inelastic $ep$ scattering using an integrated luminosity of 45 pb-1 taken with the ZEUS detector at HERA. The measurements were made in the hadronic centre-of-mass system. The analysis exploits the energy-flow method, which allows the measurement to be made over a larger range of pseudorapidity compared to previous results. The dependence of the moments of the azimuthal distributions on the pseudorapidity and minimum transverse energy of the final-state hadrons are presented. Although the predictions from next-to-leading-order QCD describe the data better than do the Monte Carlo models incorporating leading-logarithm parton showers, they still fail to describe the magnitude of the asymmetries. This suggests that higher-order calculations may be necessary to describe these data.

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ZEUS Collaboration. 2006-08-21. Measurement of azimuthal asymmetries in neutral current deep inelastic scattering at HERA. https://doi.org/10.1140/epjc%2Fs10052-007-0310-y

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