{"paper":{"title":"Insights into $Q^2 \\bar{Q}^2$ states from an effective perspective","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"hep-ph","authors_text":"Ll. Ametller, P. Talavera","submitted_at":"2015-04-24T13:41:53Z","abstract_excerpt":"We discuss the two photon coupling of the lightest scalar meson on the basis of an extension of $\\chi$PT. Using low energy data on the pion form-factor and the $\\gamma\\gamma\\to \\pi^+\\pi^-(\\pi^0\\pi^0)$ cross-sections as inputs, we find $\\Gamma(\\sigma\\to\\gamma\\gamma) \\cong 0.126~\\rm{keV} $. The smallness of the result and the relative weight between its components, ${\\Gamma_{\\gamma\\gamma\\to S_1}\\over \\Gamma{ \\gamma\\gamma\\to\\pi\\pi\\to S_1}} < 1$, suggests that the scalar $0^{++}$ meson is mainly a $Q^2\\bar{Q}^2$ state."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1504.06505","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"}