Spectrum of the S-wave fully-heavy tetraquark states

Abstract

Abstract In present work, spectrum of the S-wave fully-heavy tetraquark states $$QQ\bar{Q}\bar{Q}$$ Q Q Q ¯ Q ¯ ( $$Q=c,b$$ Q = c , b ), i.e., $$cc\bar{c}\bar{c}$$ c c c ¯ c ¯ , $$bb\bar{b}\bar{b}$$ b b b ¯ b ¯ , $$cc\bar{b}\bar{b}$$ c c b ¯ b ¯ / $$bb\bar{c}\bar{c}$$ b b c ¯ c ¯ , $$bc\bar{c}\bar{c}$$ b c c ¯ c ¯ / $$cc\bar{b}\bar{c}$$ c c b ¯ c ¯ , $$bb\bar{c}\bar{b}$$ b b c ¯ b ¯ / $$cb\bar{b}\bar{b}$$ c b b ¯ b ¯ , and $$bc\bar{b}\bar{c}$$ b c b ¯ c ¯ 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 $$cc\bar{c}\bar{c}$$ c c c ¯ c ¯ and $$bb\bar{b}\bar{b}$$ b b b ¯ b ¯ 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 $$cc\bar{c}\bar{c}$$ c c c ¯ c ¯ tetraquark state, while it could be an orbitally or radially excited state of $$cc\bar{c}\bar{c}$$ c c c ¯ c ¯ system. On the other hand, the recently reported X(6600) state by CMS and ATLAS can be explained as a ground $$cc\bar{c}\bar{c}$$ c c c ¯ c ¯ tetraquark state with spin-parity $$J^{PC} =0^{++}$$ J PC = 0 + + .