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 m_s/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 \eta_c 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 D_s mesons. We compare f_D and f_{D_s} with f_K and f_\pi, and using experiment determine corresponding CKM elements with good precision.
@article{arxiv.0709.4628,
title = {Precision Lattice Calculation of D and Ds decay constants},
author = {Eduardo Follana},
journal= {arXiv preprint arXiv:0709.4628},
year = {2011}
}
Comments
To be published in the proceedings of CHARM07, Ithaca, NY, August 2007, eConf C070805