Observation of a New Excited $D^+_s$ Meson in $B^0 \rightarrow D^- D^+ K^+ \pi^-$ Decays

Physical review letters 126(12), 122002 (2021). doi:10.1103/PhysRevLett.126.122002
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 $B^0��� D^-D^+K^+��^-$ decay is studied. A new excited $D_s^+$ meson is observed decaying into the $D^+K^+��^-$ 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, $��_R=89��16��12$ 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 $D_s^0(2590)^+$, is a strong candidate to be the $D_s(2S10)^+$ state, the radial excitation of the pseudoscalar ground-state $D_s^+$ meson.
Published by APS, College Park, Md.