{"paper":{"title":"Measurement of $J/\\psi$ helicity distributions in inelastic photoproduction at HERA","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"hep-ex","authors_text":"ZEUS Collaboration","submitted_at":"2009-06-08T07:49:30Z","abstract_excerpt":"The $J/\\psi$ 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 $J/\\psi$ mesons were identified through their decay into muon pairs. The polar and azimuthal angles of the $\\mu^+$ were measured in the $J/\\psi$ rest frame and compared to theoretical predictions at leading and next-to-leading order in QCD."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"0906.1424","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}