Quantum numbers of Ωc 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 Omega(c) states, we have identified Omega(c)(3090) and Omega(c)(3119) with radially excited 1/2(+)(2S) and 3/2(+)(2S) states, respectively, and Omega(c)(3000) with 1/2(-)(1P). The two states Omega(c)(3050) and Omega(c)(3066) form a P-wave (3/2(-), 5/2(-)) doublet. (ii) The widths of Omega(c)(3066) and Xi '(c)(2930) are calculable within the framework of heavy hadron chiral perturbation theory. (iii) Since the width of Omega(c0)(1/2(-)) is of order 410 MeV, not all observed narrow Omega(c) baryons can be identified with 1P states. (iv) For the antitriplet Lambda(c) and Xi(c) states, their Regge trajectories for the orbital excitations of 1/2(-) and 3/2(-) are parallel to each other. Based on this nice property of parallelism, we see that the highest state Lambda(c)(2940) does not fit if its quantum numbers are 3/2(-) as found by LHCb. We suggest that Lambda(c)(2940)(+) is most likely the 1/2(-)(2P) state. (v) The charmed baryon Sigma(c)(2800) cannot be a 1/2(-) state; otherwise, its width will be over 400 MeV, too large compared to the measured one. (vi) In the study of Regge trajectories of Xi '(c) states, we find a missing state. It should have quantum numbers 5/2(-) with a mass around 2920 MeV. (vii) Antitriplet and sextet states are classified according to their J(P)(nL) quantum numbers. The mass differences between Xi(c) and Lambda(c) in the antitriplet states clearly lie between 180 and 200 MeV. Moreover, the mass splitting between Omega(c) and Xi '(c) is found to be very close to the one between Xi '(c) and Sigma(c) for five different sets of sextet multiplets. This lends a strong support to the quantum number assignment to the sextet states in this work.