Coupled-channel study of baryon resonances with charm

Abstract

Identifying a zero-range exchange of vector mesons as the driving force for the s-wave scattering of pseudo-scalar mesons off the baryon ground states, a rich spectrum of molecules is formed. We argue that chiral symmetry and large-$N_c$ considerations determine that part of the interaction which generates the spectrum. A bound state with exotic quantum numbers is predicted at mass 2.78 GeV. It couples strongly to the $(\bar D_s N),(\bar D \Lambda ),(\bar D \Sigma)$ channels. A further charm minus-one system is predicted at mass 2.84 GeV as a result of $(\bar D_s \Lambda), (\bar D \Xi)$ interactions. The two so far observed s-wave baryons with charm one are recovered. We argue that the $\Lambda_c(2880)$ is not a s-wave state. In addition to those states we predict the existence of about ten narrow s-wave baryon states with masses below 3 GeV. A triplet of crypto-exotic states decaying dominantly into channels with an $\eta'$ is obtained with masses 4.24 GeV and 4.44 GeV.