Chiral dynamics for exotic open-charm resonances

Abstract

We review the open-charm spectrum of chiral excitations in QCD. At leading order in a chiral expansion a parameter-free prediction is obtained for the coupled-channel scattering of Goldstone bosons off open-charm mesons and baryons with 0^-,1^- and {1/2}^+ quantum numbers. The recently announced narrow D_s(2317) and $D_s(2463)$ mesons observed by the BABAR and CLEO collaborations are reproduced. Also the baryon states \Lambda_{c}(2593), \Lambda_{c}(2880) and \Xi_{c}(2790) discovered earlier by the CLEO collaboration are recovered naturally. Besides describing resonances with conventional quantum numbers additional multiplets with members that carry exotic quantum numbers are predicted. In particular, so far unobserved narrow isospin-singlet open-charm mesons with negative strangeness are generated dynamically. Similarly, narrow isospin-doublet open-charm baryons with positive strangeness are suggested.