Pseudoscalar decay constants fD and fDs in lattice QCD with exact chiral symmetry

We determine the masses and decay constants of pseudoscalar mesons D, Ds, and K in quenched lattice QCD with exact chiral symmetry. For 100 gauge configurations generated with single-plaquette action at β=6.1 on the 203×40 lattice, we compute point-to-point quark propagators for 30 quark masses in the range 0.03⩽mqa⩽0.80, and measure the time-correlation functions of pseudoscalar and vector mesons. The inverse lattice spacing a−1 is determined with the experimental input of fπ, while the strange quark bare mass msa=0.08, and the charm quark bare mass mca=0.80 are fixed such that the masses of the corresponding vector mesons are in good agreement with ϕ(1020) and J/ψ(3097), respectively. Our results of pseudoscalar-meson decay constants are fK=152(6)(10)MeV, fD=235(8)(14)MeV, and fDs=266(10)(18)MeV.