{"paper":{"title":"Disentangling the Decay Observables in $B^- \\to \\pi^+\\pi^-\\ell^-\\bar\\nu_\\ell$","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"hep-ph","authors_text":"Alexander Khodjamirian, Danny van Dyk, Sven Faller, Thomas Mannel, Thorsten Feldmann","submitted_at":"2013-10-24T16:33:58Z","abstract_excerpt":"We study the semileptonic $b\\to u$ transition in the decay mode $B^-\\to \\pi^+\\pi^-\\ell^-\\bar\\nu_\\ell$. We define $B\\to \\pi \\pi$ form factors in the helicity basis, and study their properties in various kinematic limits, including form factor relations in the heavy-mass and large-energy limits, the decomposition into partial waves of the dipion system, and the resonant contribution of vector and scalar mesons. We show how angular observables in $B^-\\to \\pi^+\\pi^-\\ell^-\\bar\\nu_\\ell$ can be used to measure dipion form factors or to perform null tests of the Standard Model."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1310.6660","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"}