Pentaquark states with the QQQqq¯ configuration in a simple model

Abstract

We discuss the mass splittings for the S-wave triply heavy pentaquark states with the QQQqq¯ (Q= b, c; q= u, d, s) configuration which is a mirror structure of QQ¯ qqq. The latter configuration is related with the nature of Pc(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. Ξ ccD, 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.