  We match continuum and lattice heavy-light four-fermion operators at one loop
in perturbation theory. For the heavy quarks we use nonrelativistic QCD and for
the massless light quarks the highly improved staggered quark action. We
include the full set of $\Delta B=2$ operators relevant to neutral $B$ mixing
both within and beyond the Standard Model and match through order $\alpha_s$,
$\Lambda_{\mathrm{QCD}}/M_b$, and $\alpha_s/(aM_b)$.
