Charm physics with overlap fermions on 2+1-flavor domain wall fermion configurations

Decay constants of pseudoscalar mesons D, Dₛ, ηc and vector mesons D^*, Dₛ^*, J/ψ are determined from Nf=2+1 lattice QCD at a lattice spacing a~0.08 fm. For vector mesons, the decay constants defined by tensor currents are given in the MS̄ scheme at $2$ GeV. The calculation is performed on domain wall fermion configurations generated by the RBC-UKQCD Collaborations and the overlap fermion action is used for the valence quarks. Comparing the current results with our previous ones at a coarser lattice spacing a~0.11 fm gives us a better understanding of the discretization error. We obtain fDₛ^*T( MS̄,2 GeV)/fDₛ^*=0.907(20) with a better precision than our previous result. Combining our fDₛ^*=277(11) MeV with the total width of Dₛ^* determined in a recent work gives a branching fraction 4.26(52)×10⁻⁵ for Dₛ^* leptonic decay.