Determination of |V(us)|| from a lattice QCD calculation of the K → πℓν 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 Simone; R Sugar; D Toussaint; R S Van de Water; Ran Zhou; Fermilab Lattice and MILC Collaborations

doi:10.1103/PhysRevLett.112.112001

Determination of |V(us)|| from a lattice QCD calculation of the K → πℓν semileptonic form factor with physical quark masses

Phys Rev Lett. 2014 Mar 21;112(11):112001. doi: 10.1103/PhysRevLett.112.112001. Epub 2014 Mar 17.

Authors

A Bazavov¹, C Bernard², C M Bouchard³, C Detar⁴, Daping Du⁵, A X El-Khadra⁶, J Foley⁴, E D Freeland⁷, E Gámiz⁸, Steven Gottlieb⁹, U M Heller¹⁰, Jongjeong Kim¹¹, A S Kronfeld¹², J Laiho¹³, L Levkova⁴, P B Mackenzie¹², E T Neil¹⁴, M B Oktay⁴, Si-Wei Qiu⁴, J N Simone¹², R Sugar¹⁵, D Toussaint¹¹, R S Van de Water¹², Ran Zhou¹⁶; Fermilab Lattice and MILC Collaborations

Affiliations

¹ Physics Department, Brookhaven National Laboratory, Upton, New York 11973, USA and Department of Physics and Astronomy, University of Iowa, Iowa 52242, USA.
² Department of Physics, Washington University, St. Louis, Missouri 63130, USA.
³ Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
⁴ Physics Department, University of Utah, Salt Lake City, Utah 84112, USA.
⁵ Physics Department, University of Illinois, Urbana, Illinois 61801, USA.
⁶ Physics Department, University of Illinois, Urbana, Illinois 61801, USA and Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA.
⁷ Liberal Arts Department, School of the Art Institute of Chicago, Chicago, Illinois 60603, USA.
⁸ CAFPE and Departamento de Física Teórica y del Cosmos, Universidad de Granada, E-18071 Granada, Spain.
⁹ Department of Physics, Indiana University, Bloomington, Indiana 47405, USA.
¹⁰ American Physical Society, Ridge, New York 11961, USA.
¹¹ Department of Physics, University of Arizona, Tucson, Arizona 85721, USA.
¹² Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA.
¹³ SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom and Department of Physics, Syracuse University, Syracuse, New York 13244, USA.
¹⁴ Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA and RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973, USA.
¹⁵ Department of Physics, University of California, Santa Barbara, California 93106, USA.
¹⁶ Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA and Department of Physics, Indiana University, Bloomington, Indiana 47405, USA.

PMID: 24702353
DOI: 10.1103/PhysRevLett.112.112001

Abstract

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 |V(us)| = 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 |V(us)| is now comparable to that from |V(ud)|.