We present results for the decay constants $f_B$ and $f_{B_s}$ and update our earlier determinations of $f_D$ and $f_{D_s}$. We employ HISQ ensembles with 2+1+1 flavors generated at six lattice spacings, including five with physical light-quark masses. Calculations are carried out with several heavy valence-quark masses ranging from near charm to bottom (at the finest lattice spacing). In addition to the decay constants, we present results for charm- and bottom-quark masses extracted from heavy-light meson masses using an approach based on HQET and employing the renormalon-subtracted (RS) mass as an intermediate quantity. We also present our results for the HQET parameters $\bar\Lambda$ and $\mu_\pi^2$ in the RS scheme.

Weak Decays and Matrix Elements