Decay constants of charm and beauty pseudoscalar heavy–light mesons on fine lattices

Abstract We compute decay constants of heavy–light mesons in quenched lattice QCD with a lattice spacing of a ≃ 0.04 fm using non-perturbatively O ( a ) improved Wilson fermions and O ( a ) improved currents. We obtain f D s = 220 ( 6 ) ( 5 ) ( 11 ) MeV , f D = 206 ( 6 ) ( 3 ) ( 22 ) MeV , f B s = 205 ( 7 ) ( 26 ) ( 17 ) MeV and f B = 190 ( 8 ) ( 23 ) ( 25 ) MeV , using the Sommer parameter r 0 = 0.5 fm to set the scale. The first error is statistical, the second systematic and the third from assuming a ± 10 % uncertainty in the experimental value of r 0 . A detailed discussion is given in the text. We also present results for the meson decay constants f K and f π and the ρ meson mass.