Spectroscopy and decays of the fully-heavy tetraquarks

We discuss the possible existence of the fully-heavy tetraquarks. We calculate the ground-state energy of the bb b̄ b̄ bound state, where b stands for the bottom quark, in a nonrelativistic effective field theory framework with one-gluon-exchange (OGE) color Coulomb interaction, and in a relativized diquark model characterized by OGE plus a confining potential. Our analysis advocates the existence of uni-flavor heavy four-quark bound states. The ground state bbb̄b̄ tetraquark mass is predicted to be (18.72± 0.02) GeV. Mass inequality relations among the lowest QQQ̄Q̄ states, where Q∈ , b\ , and the corresponding heavy quarkonia are presented, which give the upper limit on the mass of ground state QQQ̄Q̄ . The possible decays of the lowest bbb̄b̄ are highlighted, which might provide useful references in the search for them in ongoing LHC experiments, and its width is estimated to be a few tens of MeV.