Quantum numbers of Ω c states and other charmed baryons

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 Ωc states, we have identified Ωc(3090) and Ωc(3119) with radially excited 12+(2S) and 32+(2S) states, respectively, and Ωc(3000) with 12−(1P). The two states Ωc(3050) and Ωc(3066) form a P-wave (32−,52−) doublet. (ii) The widths of Ωc(3066) and Ξc′(2930) are calculable within the framework of heavy hadron chiral perturbation theory. (iii) Since the width of Ωc0(12−) is of order 410 MeV, not all observed narrow Ωc baryons can be identified with 1P states. (iv) For the antitriplet Λc and Ξc states, their Regge trajectories for the orbital excitations of 12− and 32− are parallel to each other. Based on this nice property of parallelism, we see that the highest state Λc(2940) does not fit if its quantum numbers are 32− as found by LHCb. We suggest that Λc(2940)+ is most likely the 12−(2P) state. (v) The charmed baryon Σc(2800) cannot be a 12− state; otherwise, its width will be over 400 MeV, too large compared to the measured one. (vi) In the study of Regge trajectories of Ξc′ states, we find a missing state. It should have quantum numbers 52− with a mass around 2920 MeV. (vii) Antitriplet and sextet states are classified according to their JP(nL) quantum numbers. The mass differences between Ξc and Λc in the antitriplet states clearly lie between 180 and 200 MeV. Moreover, the mass splitting between Ωc and Ξc′ is found to be very close to the one between Ξc′ and Σc for five different sets of sextet multiplets. This lends a strong support to the quantum number assignment to the sextet states in this work.