Bound states of charmed baryons and antibaryons

Abstract

Within the framework of nonrelativistic potential models, we investigate the possibility that bound states of the type B-bar/sub c/B/sub c/ may exist, where B/sub c/ is a charmed member of the 20 baryon multiplet of SU(4). By rather general considerations, we establish the approximate level order of the bound-state spectrum. Specific potential models are then invoked to qualitatively estimate the binding energies and rms radii of B-bar/sub c/B/sub c/ bound states. For reasonably small binding energies ( or =0.7 fm) than the corresponding c-barc quark-model states. We show that most of the low-lying states are isospin I = 0 as in the c-barc model. However, because of the coherent effect of tensor forces, certain I = 1 configurations of the C-bar/sub 1/C/sub 1/ system experience a downward energy shift, and hence could appear in the same energy region as I = 0 states (e.g., /sup 2I ts(ts1,2S/L/sub J/ = /sup 33/P/sub 0/ state near /sup 13/P/sub 0,1,2/ states). The states we describe can mix with and modify the properties of c-barc quark states ofmore » the same quantum numbers in the J/psi,chi,psi' region from 3.1 to 3.7 GeV. Some of them could appear independently as narrow states in the mass region of 4 GeV. ''Exotic'' C-bar/sub 1/C/sub 1/ states with I = 2 are shown to always lie above I = 0,1 configurations of the same L; however, for a wide class of potential models, the P-wave C-bar/sub 1/C/sub 1/ states (/sup 53/P/sub 0,1,2/,/sup 51/P/sub 1/) are still bound close to threshold (approx.4.8 GeV). We exhibit qualitative arguments that some of these B-bar/sub c/B/sub c/ bound states may be narrow. We discuss possible experimental means for finding the I = 1 and 2 states, i.e., those not predicted by the cc-bar quark model.« less