Observation of the Tcc̄1(4430)⁻ state in B⁰→ D*-D⁰K⁺ decays

A study of resonant structures in B⁰ → D*-D⁰K⁺ decays is presented. The analysis uses proton-proton collision data collected by the LHCb experiment at center-of-mass energies of √s = 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb⁻¹. The analysis demonstrates that the existing known excited Dₛ⁺ resonances in the D⁰K⁺ spectrum are insufficient to describe the data. The inclusion of the tetraquark state Tcc̄1(4430)⁻ improves the description of the data with a statistical significance exceeding $5σ$. This corresponds to the first observation of the Tcc̄1(4430)⁻ → D*- D⁰ decay. The measured properties of the Tcc̄1(4430)⁻ state are consistent with those previously measured in its decay to the ψ(2S)π⁻ final state.