{"paper":{"title":"Observation of a new charmonium state in double charmonium production in e+ e- annihilation at \\sqrt{s} ~ 10.6 GeV","license":"","headline":"","cross_cats":[],"primary_cat":"hep-ex","authors_text":"et al, The Belle Collaboration: K. Abe","submitted_at":"2005-07-04T15:47:25Z","abstract_excerpt":"We report the first observation of a new charmonium state at a mass of $(3.943 \\pm 0.006 \\pm 0.006) {GeV}/c^2$. This state, called X(3940), is observed in the process $e^+ e^- \\to J/\\psi X(3940)$ in the spectrum of masses recoiling against a reconstructed $J/\\psi$. We also observe the decay of the X(3940) into $D^* \\bar{D}$ and measure the intrinsic width of this state to be less than $52 MeV/c^2$ at the 90% C.L. These results are obtained from a $350 fb^{-1}$ data sample collected with the Belle detector near the $\\Upsilon(4S)$ resonance, at the KEKB asymmetric energy $e^+ e^-$ collider."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"hep-ex/0507019","kind":"arxiv","version":3},"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/0507019/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"}