P _c resonances in the compact pentaquark picture

P c resonances are studied in the approach of quark model and group theory. It is found that there are totally 17 possible pentaquark states with the quark contents q3QQ¯ (q are u and d quarks; Q is c quark) in the compact pentaquark picture, where the hidden charm pentaquark states may take the color singlet-singlet ([111]qqq[111]cc¯) and color octet-octet ([21]qqq[21]cc¯) configurations. The theoretical results of partial decay widths of the pentaquark states show that open charm channels are the dominant decay modes for almost all hidden charm pentaquark states, but there are four pentaquark states which decay through the pJ/ψ channel with sizable partial decay widths.