Property of cn-n¯c¯ System in Ũ(12)-Scheme and X(3872)/Y(3940)

The properties of four quark cn-n¯c¯ states are investigated as cn di-quark and n¯c¯ di-antiquark system in Ũ(12)-classification scheme of hadrons. We consider the negative-parity di-quark and di-antiquark in ground states, and the properties of X(3872) and Y(3940) are consistent, respectively, with those of the J^PC = 1⁺⁺ and 2⁺⁺ states from these negative-parity di-quark and di-antiquark. Their narrow-widths are explained from a kind of conservation law, called ρ₃-line rule. The properties of ground-state cs-s¯c¯ system are also predicted in this scheme.