{"paper":{"title":"Leptonic decay-constant ratio f_{K^+}/f_{pi^+} from lattice QCD with physical light quarks","license":"http://creativecommons.org/licenses/publicdomain/","headline":"","cross_cats":["hep-lat"],"primary_cat":"hep-ph","authors_text":"A. Bazavov, C. Bernard, C. DeTar, D. Toussaint, J. E. Hetrick, J. Foley, J. Kim, J. Laiho, J. Osborn, L. Levkova, M. Lightman, R. L. Sugar, R. S. Van de Water, R. Zhou, S. Qiu, Steven Gottlieb, U. M. Heller, W. Freeman","submitted_at":"2013-01-24T18:18:27Z","abstract_excerpt":"A calculation of the ratio of leptonic decay constants f_{K^+}/f_{\\pi^+} makes possible a precise determination of the ratio of CKM matrix elements |V_{us}|/|V_{ud}| in the Standard Model, and places a stringent constraint on the scale of new physics that would lead to deviations from unitarity in the first row of the CKM matrix. We compute f_{K^+}/f_{\\pi^+} numerically in unquenched lattice QCD using gauge-field ensembles recently generated that include four flavors of dynamical quarks: up, down, strange, and charm. We analyze data at four lattice spacings a ~ 0.06, 0.09, 0.12, and 0.15 fm wi"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1301.5855","kind":"arxiv","version":3},"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"}