Observation of the open-charm tetraquark candidate $T_{cs0}^{\ast }(2870{)}^0$ in the $B^{-}\to D^{-}{D}^0{K}_{\mathrm{S}}^0$ decay

Abstract

An amplitude analysis of $B^{-}\to D^{-}{D}^0{K}_{\mathrm{S}}^0$ decays is performed using proton-proton collision data, corresponding to an integrated luminosity of $9{\text{fb}}^{-1}$, collected with the LHCb detector at center-of-mass energies of 7, 8, and 13$\mathrm{Te}\mathrm{V}$. A resonant structure of spin-parity $0^{+}$ is observed in the $D^0{K}_{\mathrm{S}}^0$ invariant-mass spectrum with a significance of $5.3\ddot{I}ƒ$. The mass and width of the state, modeled with a Breit$-$Wigner lineshape, are determined to be $2883\pm 11\pm 8\mathrm{Me}\mathrm{V}/c^2$ and $87_{-47}^{+22}\pm 17\mathrm{Me}\mathrm{V}$ respectively, where the first uncertainties are statistical and the second systematic. These properties and the quark content are consistent with those of the open-charm tetraquark candidate $T_{cs0}^{\ast }(2870{)}^0$ observed previously in the $D^{+}{K}^{-}$ final state of the $B^{-}\to D^{-}{D}^{+}{K}^{-}$ decay. This result confirms the existence of the $T_{cs0}^{\ast }(2870{)}^0$ state in a new decay mode. The $T_{cs1}^{\ast }(2900{)}^0$ state, reported in the $B^{-}\to D^{-}{D}^{+}{K}^{-}$ decay, is also searched for in the $D^0{K}_{\mathrm{S}}^0$ invariant-mass spectrum of the $B^{-}\to D^{-}{D}^0{K}_{\mathrm{S}}^0$ decay, without finding evidence for it.

All figures and tables, along with machine-readable versions and any supplementary material and information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/3162/ (LHCb public pages)