We present a calculation of the leptonic decay-constant ratio fK/fπ in 2+1 flavor QCD. Our data set includes five lattice spacings and pion masses reaching down below the physical one. Special emphasis is placed on a careful study of all systematic uncertainties, especially the continuum extrapolation. Our result is perfectly compatible with the first-row unitarity constraint of the Standard Model.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)