Flavor-singlet hidden charm pentaquark

Abstract

One type of hidden charm pentaquark Pcs with quark content cc̄uds in light-flavor singlet state is studied in the quark model. This state is analogous to the Pc with cc̄uud in light-flavor octet, which was observed in LHC in 2015. Considering various combinations of color, spin, and light flavor as internal quantum numbers in Pcs, we investigate the mass ordering of the Pcs's by adopting both the one-gluon exchange interaction and the instanton-induced interaction in the quark model. The most stable configuration of Pcs is identified to be total spin 1/2 in which the cc̄ is combined to be color octet and spin 1, while the uds cluster is in a color octet state. The other color octet configurations, the total spin 1/2 state with the cc̄ spin 0, and the state with total spin 3/2 and cc̄ spin 1, are found as excited states. We also discuss possible decay modes of these hidden charm pentaquarks.