Hunting for exotic doubly hidden-charm/bottom tetraquark states

We develop a moment QCD sum rule method augmented by fundamental inequalities to study the existence of exotic doubly hidden-charm/bottom tetraquark states made of four heavy quarks. Using the compact diquark-antidiquark configuration, we calculate the mass spectra of these tetraquark states. There are 18 hidden-charm ccc¯c¯ tetraquark currents with JPC=0++, 0−+, 0−−, 1++, 1+−, 1−+, 1−−, and 2++. We use them to perform QCD sum rule analyses, and the obtained masses are all higher than the spontaneous dissociation thresholds of two charmonium mesons, which are thus their dominant decay modes. The masses of the corresponding hidden-bottom bbb¯b¯ tetraquarks are all below or very close to the thresholds of the ϒ(1S)ϒ(1S) and ηb(1S)ηb(1S), except one current of JPC=0++. Hence, we suggest to search for the doubly hidden-charm states in the J/ψJ/ψ and ηc(1S)ηc(1S) channels.