Spectrum of the S-wave fully-heavy tetraquark states

In present work, spectrum of the S-wave fully heavy tetraquark states Q Q (Q) over bar (Q) over bar (Q = c, b), i.e., cc (c) over bar (c) over bar, bb (b) over bar (b) over bar, cc (b) over bar (b) over bar /bb (c) over bar (c) over bar, bc (c) over bar (c) over bar/ cc (b) over bar (c) over bar, bb (c) over bar (b) over bar /cb (b) over bar (b) over bar, and bc (b) over bar (c) over bar are systematically investigated within a nonrelativistic constituent quark model, in which the instanton-induced and one-gluon exchange interactions are taken into account as the residual spin-dependent hyperfine interaction. Our results show that the states with cc (c) over bar (c) over bar and bb (b) over bar (b) over bar; components could be located around 6500 MeV and 19,200 MeV, respectively. Based on our calculations, the new X(6900) state observed by LHCb may be not a ground cc (c) over bar (c) over bar tetraquark state, while it could be an orbitally or radially excited state of cc (c) over bar (c) over bar system. On the other hand, the recently reported X (6600) state by CMS and ATLAS can be explained as a ground cc (c) over bar (c) over bar tetraquark state with spin-parity J(PC) = 0++.

Automated summary

This study systematically investigates the fully heavy tetraquark states using a nonrelativistic constituent quark model, taking into account the instanton-induced and one-gluon exchange interactions. The results show the existence of specific states at certain energy ranges. It suggests that the newly observed X(6900) state by LHCb may be an excited state, while the reported X(6600) state by CMS and ATLAS may be a ground state tetraquark.