Observation of a New Excited Ds+ Meson in B0 → D− D+ K+ π− Decays

Abstract

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− D+ K+ π− decay is studied. A new excited Ds+ meson is observed decaying into the D+ K+ π− 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 m_R = 2591 ± 6 ± 7 MeV, Γ_R = 89 ± 16 ± 12 MeV, and J^P = 0−, where the first uncertainty is statistical and the second systematic. Fit fractions for all components in the amplitude analysis are also reported. The new resonance, denoted as Ds0(2590)+, is a strong candidate to be the Ds(2^1S_0)+ state, the radial excitation of the pseudoscalar ground-state Ds+ meson