{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"616c11bfc63a118f113fa16a68a6b796c193b3bceeaa389afabdac303d1ceb1d","created":"2026-10-03T07:18:07Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011","92f81305b482b6400d3856a69e01288ef6a9ddb630b25dfa8b749462fb37756b"],"salt":"a8e6e8faffa179f5451c66b8a55d150240c5f70d5ddbe0583df5ab04b9e953af","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"nuc.exotic-hadrons.x3872-compositeness","kind":"well-posed","literature_status":"open","n":"1","parents":[{"note":"","parent_revision":"92f81305b482b6400d3856a69e01288ef6a9ddb630b25dfa8b749462fb37756b","relation":"special_case"}],"plain":"The chi_c1(3872), also called $X(3872)$, lies within about 0.2 MeV of the combined mass of two charmed mesons, $D0$ and anti-D*0. Measuring its exact position and line shape decides how much of it is a loose two-meson molecule.","posed_since":"2003","precise":"Determine the pole position of chi_c1(3872) relative to the D0 anti-$D*0$ threshold, including the finite D*0 width, and its Weinberg compositeness $1 - Z$ ($Z = 0\\ \\text{pure molecule}, Z = 1\\ \\text{compact state}$) from the $D0\\ \\text{anti-D0}\\ \\pi0\\ \\text{and}\\ J/\\psi\\ \\pi+\\ \\pi-$ line shapes. Answer: binding energy with about $10\\,\\mathrm{keV}$ precision and Z with uncertainty below 0.1.","problem_ref":null,"references":"","settled_by":"A direct energy scan in antiproton-proton annihilation (PANDA at FAIR) or high-statistics D0 anti-D0 pi0 line shapes at LHCb or Belle II.","status_note":"LHCb line-shape analyses (2020) placed the pole very close to threshold, consistent with a quasi-bound state, without fixing Z.","title":"Compositeness of chi_c1(3872) from its line shape","topic_ref":"0a95c0555eb6bb05e3999da7d5dca17d55ffdaf922ee81ba9f8dcd197324eda0"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"24e1c781aa086d22f90ffb308030079c2dbee63dd58a84fd6b0dbfc8829e7d82","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"634129b010bf6da48b2007aef298d77c3dbf92ab4e9d479b22b389c8d2645f4a","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"rKO2Ek5Dyp_Ju8DVgHSk2u2yO1mp-wC8DTkk_EefaDtVRYQDWuYNQGM_VB6GhhqU83Qx1hrVFh-OVZvi8fslBQ"},"schema":"pubphys.envelope/1"},"record_hash":"24e1c781aa086d22f90ffb308030079c2dbee63dd58a84fd6b0dbfc8829e7d82","leaf_index":1751}