Abstract
Possible spin-parity quantum numbers for excited charmed baryon resonances are discussed in this work. Our main results are as follows. (i) Among the five newly observed states, we have identified and with radially excited and states, respectively, and with . The two states and form a -wave doublet. (ii) The widths of and are calculable within the framework of heavy hadron chiral perturbation theory. (iii) Since the width of is of order 410 MeV, not all observed narrow baryons can be identified with states. (iv) For the antitriplet and states, their Regge trajectories for the orbital excitations of and are parallel to each other. Based on this nice property of parallelism, we see that the highest state does not fit if its quantum numbers are as found by LHCb. We suggest that is most likely the state. (v) The charmed baryon cannot be a state; otherwise, its width will be over 400 MeV, too large compared to the measured one. (vi) In the study of Regge trajectories of states, we find a missing state. It should have quantum numbers with a mass around 2920 MeV. (vii) Antitriplet and sextet states are classified according to their quantum numbers. The mass differences between and in the antitriplet states clearly lie between 180 and 200 MeV. Moreover, the mass splitting between and is found to be very close to the one between and for five different sets of sextet multiplets. This lends a strong support to the quantum number assignment to the sextet states in this work.
- Received 5 April 2017
DOI:https://doi.org/10.1103/PhysRevD.95.094018
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