Pentaquark states with the QQQqbar{q} configuration in a simple model

Abstract

We discuss the mass splittings for the S-wave triply heavy pentaquark states with the QQQqbar{q}(Q=b,c;q=u,d,s) configuration which is a mirror structure of Qbar{Q}qqq. The latter configuration is related with the nature of P_c(4380) observed by the LHCb Collaboration. The considered pentaquark masses are estimated with a simple method. One finds that such states are probably not narrow even if they do exist. This leaves room for molecule interpretation for a state around the low-lying threshold of a doubly heavy baryon and a heavy-light meson, e.g. Xi _{cc}D, if it were observed. As a by product, we conjecture that upper limits for the masses of the conventional triply heavy baryons can be determined by the masses of the conventional doubly heavy baryons.