The decay constants fD and fDs in the continuum limit of Nf = 2 + 1 domain wall lattice QCD

We present results for the decay constants of the D and Ds mesons computed in lattice QCD with Nf = 2 + 1 dynamical flavours. The simulations are based on RBC/UKQCD’s domain wall ensembles with both physical and unphysical light-quark masses and lattice spacings in the range 0.11-0.07 fm. We employ the domain wall discretisation for all valence quarks. The results in the continuum limit are fD = 208.7(2.8)stat(− 1.8 + 2.1)sysMeV and fDs=246.4(1.3)stat(−1.9+1.3)sysMeV and fDs=fD=1.667(77)stat(−43+57)sys. Using these results in a Standard Model analysis we compute the predictions |Vcd| = 0.2185(50)exp(− 37 + 35)lat and |Vcs| = 1.011(16)exp(− 9 + 4)lat for the CKM matrix elements.