Fully-heavy tetraquark spectra and production at hadron colliders

Motivated by the observation of exotic structure around 6900MeV in the $J/\psi$-pair mass spectrum using proton-proton collision data by the LHCb collaboration, we study the spectra of fully-heavy tetraquarks within Regge trajectory relation. The $X(6900)$ may be explained as a radially excited state with quark content $cc\bar{c}\bar{c}$ and spin-parity $0^{++}$ or $2^{++}$ or an orbitally excited state with $1^{-+}$. New $cc\bar{c}\bar{c}$ structures around 5990MeV, 6450MeV, and 7280MeV are predicted. Other $bb\bar{b}\bar{b}$ and $bc\bar{b}\bar{c}$ structures which may be experimentally prominent are discussed. On the other hand, the fully-heavy S-wave tetraquark production at hadron colliders are investigated and their cross sections are obtained.