Perturbative QCD Evidence for Spin-2 Particles in the Di-$J/\psi$ Resonances

Hong-Fei Zhang, Yan-Qing Ma, Wen-Long Sang

We extend the nonrelativistic QCD framework to explore the nature of the newly discovered di-$J/\psi$ resonances. Assuming them as either molecule-like states or tetraquarks, we calcu…