Can X(5568) be a tetraquark state?**Supported by National Natural Science Foundation of China (11575110), Natural Science Foundation of Shanghai (15DZ2272100, 15ZR1423100), China Postdoctoral Science Foundation, Open Project Program of State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, China (Y5KF111CJ1), and Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry

Abstract

Very recently, the D0 collaboration has reported the observation of a narrow structure, X(5568), in the decay process using the 10.4fb−1 data of pp̄ collision at . This structure is of great interest since it is the first hadronic state with four different valence quark flavors, b, s, u, d. In this work, we investigate tetraquarks with four different quark flavors. Based on the diquark-antidiquark scheme, we study the spectroscopy of the tetraquarks with one heavy bottom/charm quark and three light quarks. We find that the lowest-lying S-wave state, a tetraquark with the flavor [su][b̄d̄] and the spin-parity JP = 0+, is about 150 MeV higher than the X(5568). Further detailed experimental and theoretical studies of the spectrum, production and decays of tetraquark states with four different flavors are vital to gain a better understanding of the nature and classification of hadron exotic states.