{"paper":{"title":"Extracting $\\pi\\pi$ $S$-wave scattering lengths from cusp effect in heavy quarkonium dipion transitions","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["hep-ex"],"primary_cat":"hep-ph","authors_text":"Evgeny Epelbaum, Feng-Kun Guo, Xiao-Hai Liu","submitted_at":"2012-12-17T16:54:34Z","abstract_excerpt":"Charge-exchange rescattering $\\pi^+\\pi^-\\to \\pi^0\\pi^0$ leads to a cusp effect in the $\\pi^0\\pi^0$ invariant mass spectrum of processes with $\\pi^0\\pi^0$ in the final state which can be used to measure $\\pi\\pi$ $S$-wave scattering lengths. Employing a non-relativistic effective field theory, we discuss the possibility of extracting the scattering lengths in heavy quarkonium $\\pi^0\\pi^0$ transitions. The transition $\\Upsilon(3S)\\to\\Upsilon(2S)\\pi^0\\pi^0$ is studied in details. We discuss the precision that can be reached in such an extraction for a certain number of events."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1212.4066","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":""},"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"}