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arXiv · 0906.1424

Measurement of $J/ψ$ helicity distributions in inelastic photoproduction at HERA

ZEUS Collaboration
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Abstract

The $J/ψ$ decay angular distributions have been measured in inelastic photoproduction in $e p$ collisions with the ZEUS detector at HERA, using an integrated luminosity of 468 $pb^{-1}$. The range in photon-proton centre-of-mass energy, $W$, was 50 $< W <$ 180 $GeV$. The $J/ψ$ mesons were identified through their decay into muon pairs. The polar and azimuthal angles of the $μ^+$ were measured in the $J/ψ$ rest frame and compared to theoretical predictions at leading and next-to-leading order in QCD.

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ZEUS Collaboration. 2009-06-08. Measurement of $J/ψ$ helicity distributions in inelastic photoproduction at HERA. https://doi.org/10.1088/1126-6708%2F2009%2F12%2F007

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