{"paper":{"title":"The Standard model prediction for K(e2)/K_(mu2) and pi(e2)/pi(mu2)","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"hep-ph","authors_text":"Ignasi Rosell","submitted_at":"2009-10-13T09:36:38Z","abstract_excerpt":"We have calculated the ratios $R_{e/\\mu}^{(P)} \\equiv \\Gamma(P \\to e \\bar{\\nu}_e [\\gamma])/ \\Gamma(P \\to \\mu \\bar{\\nu}_\\mu [\\gamma])$ ($P=\\pi,K$) in Chiral Perturbation Theory up to $\\mathcal{O}(e^2p^4)$, finding $R_{e/\\mu}^{(\\pi)} = (1.2352 \\pm 0.0001) \\times 10^{-4}$ and $R_{e/\\mu}^{(K)} = (2.477 \\pm 0.001) \\times 10^{-5}$. This observable is helicity suppressed in the Standard Model, so that it is a sensitive probe of all Standard Model extensions that induce pseudoscalar currents and nonuniversal corrections to the lepton couplings. Ongoing experimental searches plan to reach uncertainties"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"0910.2347","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"}