; Luo, Zhi-Gang
; Zhu, Shi-Lin] Peking Univ, Dept Phys, Beijing 100871, Peoples R China
; [Liu, Xiang] Univ Coimbra, Ctr Fis Computac, Dept Fis, P-3004516 Coimbra, Portugal
; [Liu, Yan-Rui] Inst High Energy Phys, Beijing 100049, Peoples R China
We perform a systematic study of the possible molecular states composed of a pair of heavy mesons such as D (D) over bar, D*(D) over bar, D*(D) over bar* in the framework of the meson exchange model. The exchanged mesons include the pseudoscalar, scalar and vector mesons. Through our investigation, we find the following results. (1) The structure X(3764) is not a molecular state. (2) There exists strong attraction in the range r < 1 fm for the D*(D) over bar* system with J = 0, 1. If future experiments confirm Z(+)(4051) as a loosely bound molecular state, its quantum number is probably J(P) = 0(+). Its partner state Phi**(0) may be searched for in the pi(0) chi c1 channel. (3) Vector meson exchange provides strong attraction in the D*(D) over bar channel together with pion exchange. A bound state solution may exist with a reasonable cutoff parameter. A similar to 1.4 GeV.X(3872) may be accommodated as a molecular state dynamically although drawing a very definite conclusion needs further investigation. (4) The B*(B) over bar molecular state may exist.