Leptonic decay constants fDs and fD in three flavor lattice QCD

ManuscriptWe determine the leptonic decay constants fDs and fD in three flavor unquenched lattice QCD. We use O(a2)-improved staggered light quarks and O(a)-improved charm quarks in the Fermilab heavy quark formalism. Our preliminary results, based upon an analysis at a single lattice spacing, are fDs = 263+5 −9 ± 24 MeV and fD = 225+11 −13 ± 21 MeV. In each case, the first reported error is statistical while the second is the combined systematic uncertainty