Evidence of a $J/\psi \Lambda$ structure and observation of excited ${\Xi }^{-}$ states in the ${\Xi }_b^{-}\to J/\psi \Lambda K^{-}$ decay

LHCb collaboration, R. Aaij, C. Abellán Beteta +959

First evidence of a structure in the $J/\psi \Lambda$ invariant mass distribution is obtained from an amplitude analysis of ${\Xi }_b^{-}\to J/\psi \Lambda K^{-}$ decays. The observed s…