We present a study of the D and B leptonic decay constants on the MILC Nf=2+1 asqtad gauge ensembles using asqtad-improved staggered light quarks and clover heavy quarks in the Fermilab interpretation. Our previous analysis \cite{Bazavov:2011aa} computed the decay constants at lattice spacings a≈0.14,0.11 and 0.083 fm. We have extended the simulations to finer a≈0.058 and 0.043 fm lattice spacings, and have also increased statistics; this allows us to address many important sources of uncertainty. Technical advances include a two-step two-point fit procedure, better tuning of the heavy quark masses and a better determination of the axial-vector current matching. The present analysis remains blinded, so here we focus on the improvements and their predicted impact on the error budget compared to the prior analysis.
@article{arxiv.1403.6796,
title = {The $D_s$, $D^+$, $B_s$ and $B$ decay constants from $2+1$ flavor lattice QCD},
author = {A. Bazavov and C. Bernard and C. Bouchard and C. DeTar and D. Du and A. X. El-Khadra and J. Foley and E. D. Freeland and E. Gámiz and Steven Gottlieb and U. M. Heller and J. Kim and J. Komijani and A. S. Kronfeld and J. Laiho and L. Levkova and P. B. Mackenzie and D. Mohler and E. T. Neil and M. B. Oktay and S. Qiu and J. N. Simone and R. L. Sugar and D. Toussaint and R. S. Van de Water and R. Zhou},
journal= {arXiv preprint arXiv:1403.6796},
year = {2014}
}