Study of the D 0 p amplitude in Λ b 0  → D 0 pπ − decays

An amplitude analysis of the decay 0 b D 0 p -is performed in the part of the phase space containing resonances in the D 0 p channel. The study is based on a data sample corresponding to an integrated luminosity of 3.0 fb -1 of pp collisions recorded by the LHCb experiment. The spectrum of excited + c states that decay into D 0 p is studied. The masses, widths and quantum numbers of the c (2880) + and c (2940) + resonances are measured. The constraints on the spin and parity for the c (2940) + state are obtained for the first time. A near-threshold enhancement in the D 0 p amplitude is investigated and found to be consistent with a new resonance, denoted the c (2860) + , of spin 3/2 and positive parity.