title: High-precision determination of the pi, K, D, and Ds decay constants from lattice QCD.
abstract: We determine D and D(s) decay constants from lattice QCD with 2% errors, 4 times better than experiment and previous theory: f(D(s))=241(3) MeV, f(D)=207(4) MeV, and fD(s))/f(D)=1.164(11). We also obtain f(K)/f(pi)=1.189(7) and (f(D(s))/f(D))/(f(K)/f(pi))=0.979(11). Combining with experiment gives V(us)=0.2262(14) and V(cs)/V(cd) of 4.43(41). We use a highly improved quark discretization on MILC gluon fields that include realistic sea quarks, fixing the u/d, s, and c masses from the pi, K, and eta(c) meson masses. This allows a stringent test against experiment for D and D(s) masses for the first time (to within 7 MeV).
authors: Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom.
authors: E
authors: E
authors: Follana
authors: C T H
authors: CT
authors: Davies
authors: G P
authors: GP
authors: Lepage
authors: J
authors: J
authors: Shigemitsu