Amplitude analysis of $B^0\to {\bar{D}}^0{D}_s^{+}{\pi }^{-}$ and $B^{+}\to D^{-}{D}_s^{+}{\pi }^{+}$ decays

Resonant contributions in $B^0\to {\bar{D}}^0{D}_s^{+}{\pi }^{-}$ and $B^{+}\to D^{-}{D}_s^{+}{\pi }^{+}$ decays are determined with an amplitude analysis, which is performed both separately and simultaneously, where in the latter case isospin symmetry between the decays is assumed. The analysis is based on data collected by the LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8 and 13 $\mathrm{T}\mathrm{e}\mathrm{V}$. The full data sample corresponds to an integrated luminosity of 9 $\mathrm{f}{\mathrm{b}}^{-1}$. A doubly charged spin-0 open-charm tetraquark candidate together with a neutral partner, both with masses near $2.9\mathrm{G}\mathrm{e}\mathrm{V}$, are observed in the $D_s\pi$ decay channel.