Hidden charm pentaquark states in a diquark model

The mass spectrum of hidden charm pentaquark states composed of two diquarks and an antiquark are calculated by use of an effective Hamiltonian which includes explicitly the spin, color, and flavor dependent interactions. The results show that the P_c(4312) ⁺ and P_c(4440) ⁺ states could be explained as hidden charm pentaquark states with isospin and spin-parity IJ^P= 1 / 2 (3 / 2 ^-) , the P_c(4457) ⁺ state could be explained as a hidden charm pentaquark state with IJ^P= 1 / 2 (5 / 2 ^-) , and the P_cs(4459) ⁺ state could be explained as a hidden charm pentaquark state with IJ^P= 0 (1 / 2 ^-) or 0 (3 / 2 ^-). Predications for the masses of other possible pentaquark states are also given, and the possible decay channels of these hidden charm pentaquark states are discussed.