Σc(D)over-bar and Λc(D)over-bar states in a chiral quark model

The S-wave Sigma(c)(D) over bar and Lambda(c)(D) over bar states with isospin I = 1/2 and spin S = 1/2 are dynamically investigated within the framework of a chiral constituent quark model by solving a resonating group method equation. The results show that the interaction between Sigma(c) and (D) over bar is attractive, which consequently results in a Sigma(c)(D) over bar bound state with a binding energy of about 5-42 MeV, unlike the case of the Lambda(c)(D) over bar state, which has a repulsive interaction and thus is unbound. The channel-coupling effect of Sigma(c)(D) over bar and Lambda(c)(D) over bar is found to be negligible owing to the fact that the gap between the Sigma(c)(D) over bar and Lambda(c)(D) over bar thresholds is relatively large and the Sigma(c)(D) over bar and Lambda(c)(D) over bar transition interaction is weak.