Quenched heavy-light decay constants

We present results for heavy-light decay constants, using both propagating quarks and the static approximation, in O(a)-improved, quenched lattice QCD. At β=6.2 on a 243x48 lattice we find fD=185-3+4(stat) -7+42(syst) MeV, fB=160-6-19+6+53 MeV, fDs/fD=1.18-2+2, and fBs/fB=1.22-3+4, in good agreement with earlier studies. From the static theory we obtain fBstat=253-15+16-15+105 MeV. We also present results from a simulation at β=6.0 on a 163x48 lattice, which are consistent with those at β=6.2. In order to study the effects of improvement, we present a direct comparison of the results using both the Wilson and the improved action at β=6.0