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High precision determination of the D and Ds decay constants and masses from lattice QCD

Presenter: Eduardo Follana — University of Glasgow

E. Follana, C.T.H. Davies, G.P. Lepage, J. Shigemitsu

We present a determination of the decay constants of the D and Ds mesons from lattice QCD, each with a total error of about 2%, approximately a factor of three better than previous calculations. We have been able to achieve this through the use of a highly improved discretization of QCD for charm quarks, coupled to gauge configurations generated by the MILC collaboration that include the full effect of sea u, d, and s quarks. We have results for a range of u/d masses down to ms/5 and three values of the lattice spacing, which allow us to perform accurate continuum and chiral extrapolations. We fix the charm quark mass to give the experimental value of the ηc mass, and then a stringent test of our approach is the fact that we obtain correct (and accurate) values for the mass of the D and Ds mesons. We compare fD and fDs with fK and fπ, and using experiment determine corresponding CKM elements with good precision.