We determine the ratio FK/Fπ in QCD with Nf=2+1 flavors of sea quarks, based on a series of lattice calculations with three different lattice spacings, large volumes, and a simulated pion mass reaching down to about 190 MeV. We obtain FK/Fπ=1.192(7)stat(6)syst. This result is then used to give an updated value of the Cabibbo-Kobayashi-Maskawa) matrix element |Vus|. The unitarity relation for the first row of this matrix is found to be well observed.
|Original language||English (US)|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|State||Published - Mar 22 2010|
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)