{"paper":{"title":"Search for a new gauge boson in the $A'$ Experiment (APEX)","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["hep-ph","nucl-ex"],"primary_cat":"hep-ex","authors_text":"A.Barbieri, A.Camsonne, A.Gasparian, A.Kelleher, A.Odian, A.Shahinyan, B.Sawatzky, B.Wojtsekhowski, C.Field, C.W.deJager, D.Anez, D.Walz, D.W.Higinbotham, E.Folts, E.Jensen, E.Long, E.Piasetzky, I.Pomerantz, J.Beacham, J.Bono, J.Donaghy, J.Gomez, J.Huang, J.Jaros, J.J.LeRose, J.Mammei, J.McDonald, J.-O.Hansen, J.R.Boyce, J.Segal, J.Zhang, K.Allada, K.Bartlett, K.Cranmer, K.Moffeit, L.Selvy, M.Graham, M.Khandaker, M.M.Dalton, M.Oriunno, M.Paolone, N.Goeckner-Wald, N.Liyanage, N.Toro, P.Brindza, P.Markowitz, P.Schuster, R.Essig, R.Lindgren, R.Michaels, R.Partridge, R.Subedi, S.Abrahamyan, S.Iqbal, S.Mayilyan, S.Riordan, S.Stepanyan, T.Averett, T.Holmstrom, T.Maruyama, V.Maxwell, V.Nelyubin, V.Sulkosky, Y.Qiang, Y.Roblin, Z.Ahmed","submitted_at":"2011-08-13T02:32:01Z","abstract_excerpt":"We present a search at Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling $\\alpha'$ to electrons. Such a particle $A'$ can be produced in electron-nucleus fixed-target scattering and then decay to an $e^+e^-$ pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175--250 MeV, found no evidence for an $A'\\to e^+e^-$ reaction, and set an upper limit of $\\alpha'/\\alpha \\simeq 10^{-6}$. Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1108.2750","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"}