Observation of a new excited D-s(+) Meson in B-0 -> D- D+ K+ pi(-) decays

Using pp collision data corresponding to an integrated luminosity of 5.4 fb−1 collected with the LHCb detector at a center-of-mass energy of 13 TeV, the B0 → D−DþKþπ− decay is studied. A new excited Dþ s meson is observed decaying into the DþKþπ− final state with large statistical significance. The pole mass and width, and the spin parity of the new state are measured with an amplitude analysis to be mR ¼2591 6 7MeV,ΓR ¼89 16 12MeV,andJP ¼0−,wherethefirstuncertaintyisstatistical and the second systematic. Fit fractions for all components in the amplitude analysis are also reported. The newresonance, denoted as Ds0ð2590Þþ, is a strong candidate to be the Dsð21S0Þþ state, the radial excitation of the pseudoscalar ground-state Dþ s meson.