We study the presence of the $D_{s0}^{\ast}(2317)$ resonance in the weak decay process: $B_c\to J/\psi KD$. We assume a weak interaction mechanism in which the $b$ quark decays into a $c\bar{c}$ ($J/\psi$) and $\bar{s}$ via a $W$ meson. In this process the $c\bar{s}$ pair hadronizes and the possible final configurations considered are $KD$ and $\eta D_s$. We compute the interaction of these two meson channels in the chiral unitary approach. Then we consider the $D_{s0}^{\ast}(2317)$ as mainly a $KD$ molecular state, and we fit the parameters of the theory in order to get a bound state pole in the S-matrix at the experimental mass of the $D_{s0}^{\ast}(2317)$. We also consider the possibility of an additional q anti-q component in the $D_{s0}^{\ast}(2317)$, introducing a CDD pole in the potential that describes the interaction. In these possible scenarios we predict the ratio of the invariant mass distribution $(B_c\to J/\psi KD)/(B_c\to D_{s0}^{\ast}(2317))$. In all cases the invariant mass distribution peaks very close to the KD threshold suggesting the presence of the $D_{s0}^{\ast}(2317)$ resonance.

Based on "$D^{\ast}_{s0}(2317)^+$ in the decay of $B_c$ into $J/\psi DK$". Phys. Rev. D, in print. arXiv:1510.06316 [hep-ph].