{"paper":{"title":"First Observation of $P$-odd $\\gamma$ Asymmetry in Polarized Neutron Capture on Hydrogen","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["hep-ex"],"primary_cat":"nucl-ex","authors_text":"A. Barzilov, A. Ramirez-Morales, A. Salas-Bacci, A. Sprow, B. Lauss, C. B. Crawford, C.E. Coppola, C. Fieseler, C. Hayes, D. Blyth, D. Evans, D.J. Turkoglu, D. Parsons, D. Po\\v{c}ani\\'c, E. Askanazi, E.B. Iverson, E. Frle\\v{z}, E.I. Sharapov, E. Scott, E. Tang, F. Simmons, G.L. Greene, H. Nann, I. Garishvili, I. Novikov, J.D. Bowman, J. Fry, J. Hall, J. Hamblen, J. Mei, J.R. Calarco, J. Stewart, K.B. Grammer, K. Craycraft, L. Alonzi, L. Barr\\'on-Palos, M.L. Kabir, M. Maldonado-Vel\\'azquez, M. McCrea, M. Musgrave, M. Root, M.T.W. Gericke, N. Birge, N. Fomin, P.E. Mueller, P.-N. Seo, R. Alarcon, R.C. Gillis, R. Mahurin, R. Milburn, R. Whitehead, S. Bae{\\ss}ler, S. Balascuta, S.I. Penttil\\\"a, S. Kucuker, S. Santra, S. Schr\\\"oder, T.E. Chupp, V. Cianciolo, W.M. Snow, W.S. Wilburn, X. Tong, Y. Masuda, Z. Tang","submitted_at":"2018-07-26T15:22:21Z","abstract_excerpt":"We report the first observation of the parity-violating 2.2 MeV gamma-ray asymmetry $A^{np}_\\gamma$ in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. $A^{np}_\\gamma$ isolates the $\\Delta I=1$, \\mbox{$^{3}S_{1}\\rightarrow {^{3}P_{1}}$} component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless EFT. We measured $A^{np}_\\gamma = [-3.0 \\pm 1.4 (stat) "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1807.10192","kind":"arxiv","version":2},"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"}