Determination of | Vus | from a lattice QCD calculation of the K → π ℓ ν Semileptonic form factor with physical quark masses

A. Bazavov, C. Bernard, C. M. Bouchard, C. Detar, Daping Du, A. X. El-Khadra, J. Foley, E. D. Freeland, E. Gámiz, Steven Gottlieb, U. M. Heller, Jongjeong Kim, A. S. Kronfeld, J. Laiho, L. Levkova, P. B. Mackenzie, E. T. Neil, M. B. Oktay, Si Wei Qiu, J. N. SimoneR. Sugar, D. Toussaint, R. S. Van De Water, Ran Zhou

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39 Scopus citations


We calculate the kaon semileptonic form factor f+(0) from lattice QCD, working, for the first time, at the physical light-quark masses. We use gauge configurations generated by the MILC Collaboration with Nf=2+1+1 flavors of sea quarks, which incorporate the effects of dynamical charm quarks as well as those of up, down, and strange. We employ data at three lattice spacings to extrapolate to the continuum limit. Our result, f+(0)=0.9704(32), where the error is the total statistical plus systematic uncertainty added in quadrature, is the most precise determination to date. Combining our result with the latest experimental measurements of K semileptonic decays, one obtains the Cabibbo-Kobayashi-Maskawa matrix element |Vus|=0.22290(74)(52), where the first error is from f+(0) and the second one is from experiment. In the first-row test of Cabibbo-Kobayashi-Maskawa unitarity, the error stemming from |Vus| is now comparable to that from |Vud|.

Original languageEnglish (US)
Article number112001
JournalPhysical review letters
Issue number11
StatePublished - Mar 17 2014

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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