  We review some decays that require knowledge of the decay constants of
$0^{+}$ heavy-light mesons. We compute the decay constants of P-wave
heavy-light mesons from unquenched lattice QCD, with two degenerate flavours of
sea quarks, at a single lattice spacing. The lightest sea quark mass used in
the calculation is a third of the strange quark mass. For the charm-strange
meson we obtain the decay constant: $f_{D_{s 0^+}} = 340(110)$ MeV using our
normalisation conventions. We obtain the $f_{P_s}^{static}$ (static-strange
P-wave) decay constant as $302(39)$ MeV.
