{"paper":{"title":"Beam-Helicity Asymmetries in Double Pion Photoproduction off the Proton","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"nucl-ex","authors_text":"A. Braghieri, A. Fix, A. Knezevic, A. Kulbardis, A. Nikolaev, A. Polonski, A. Starostin, A. Thomas, B. Boillat, B. Krusche, B.M.K. Nefkens, C.M. Tarbert, D. Branford, D. Hornidge, D.I. Glazier, D. Krambrich, D. Mekterovic, D.M. Manley, D.P. Watts, D. Sober, E. Heid, E.J. Downie, F. Pheron, F. Zehr, G. Rosner, H.J. Arends, I.J.D. MacGregor, I. Supek, J. Ahrens, J. Brudvik, J.C. McGeorge, J.R.M. Annand, J.W. Price, K. Livingston, L. Roca, M. Korolija, M. Kotulla, M. Lang, M. Martinez, M. Rost, M. Unverzagt, O. Jahn, P. Aguar, P. Dexler, P. Grabmayr, P. Pedroni, R. Beck, R. Codling, R. Gregor, R. Kondratiev, S. Cherepnya, S. Lugert, S.N. Prakhov, S. Schumann, Th. Walcher, T. Rostomyan, V. Bekrenev, V. Lisin, V.L. Kashevarov, V. Metag, W.J. Briscoe","submitted_at":"2009-07-02T12:17:32Z","abstract_excerpt":"Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz in the three isospin channels $\\vec{\\gamma}p\\to \\pi^{+}\\pi^0n$, $\\vec{\\gamma}p\\to \\pi^{0}\\pi^0p$ and $\\vec{\\gamma}p\\to \\pi^{+}\\pi^{-}p$ . The circularly polarized photons, produced from bremsstrahlung of longitudinally polarized electrons, were tagged with the Glasgow magnetic spectrometer. Charged pions and the decay photons of $\\pi^0$ mesons were detected in a $~4\\pi$ electromagnetic calorimeter which combined the Crystal Ball detector with the TAPS detector. The precisely measured asymmetries are very sensitive to"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"0907.0358","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":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/0907.0358/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"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"}