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

We present results for the decay constants of the D and D s mesons computed in lattice QCD with N f = 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 f D = 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 |V cd | = 0.2185(50)exp( − 37 + 35 )lat and |V cs | = 1.011(16)exp( − 9 + 4 )lat for the CKM matrix elements.