{"paper":{"title":"A Measurement of the Mass and Full-Width of the $\\eta_c$ Meson","license":"","headline":"","cross_cats":[],"primary_cat":"hep-ex","authors_text":"et al. (BES Collaboration), J. Z. Bai","submitted_at":"2000-02-03T08:45:07Z","abstract_excerpt":"In a sample of 7.8 million $J/\\psi$ decays collected in the Beijing Spectrometer, the process J/$\\psi\\to\\gamma\\eta_c$ is observed for five different $\\eta_c$ decay channels: $K^+K^-\\pi^+\\pi^-$, $\\pi^+\\pi^-\\pi^+\\pi^-$, $K^\\pm K^0_S \\pi^\\mp$ (with $K^0_S\\to\\pi^+\\pi^-$), $\\phi\\phi$ (with $\\phi\\to K^+K^-$) and $K^+K^-\\pi^0$. From these signals, we determine the mass of $\\eta_c$ to be $2976.6\\pm2.9\\pm1.3$ MeV. Combining this result with a previously reported result from a similar study using $\\psi(2S)\\to\\gamma\\eta_c$ detected in the same spectrometer gives $m_{\\eta_c} = 2976.3\\pm2.3\\pm1.2$ MeV. For"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"hep-ex/0002006","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/hep-ex/0002006/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"}