The $B^{+}\to J\mathrm{/}\psi \omega K^{+}$ reaction and $D^{\ast }{\bar{D}}^{\ast }$ molecular states

We study the $B^{+}\to J\mathrm{/}\psi \omega K^{+}$ reaction, measured by the LHCb collaboration, and show that it is driven by the presence of two resonances, the $X(3940)$ and $X(3930)$, that are of molecular nature and couple most strongly to $D^{\ast }{\bar{D}}^{\ast }$, but also to $J\mathrm{/}\psi \omega$. Because of that, in the $J\mathrm{/}\psi \omega$ mass distribution we find a peak related to the excitation of the resonances and a cusp with large strength at the $D^{\ast }{\bar{D}}^{\ast }$ threshold.