Physics

Particle physics

Excited state

Nuclear physics

Hadron

Parity (physics)

Tetraquark

Exotic hadron

Spectral line

Proton

Quantum mechanics

Mass spectrum

Quark

Nuclear Physics B

Motivated by the observation of exotic structure around 6900 MeV in the J/ψ-pair mass spectrum using proton-proton collision data by the LHCb collaboration, we study the spectra of fully-heavy tetraquarks within Bethe-Salpeter equation and Regge trajectory relation. The X(6900) may be explained as a radially excited state with quark content ccc¯c¯ and spin-parity 0++(3S) or 2++(3S) or an orbitally excited 2P state. New ccc¯c¯ structures around 6.0 GeV, 6.5 GeV, and 7.1 GeV are predicted together. Other bbb¯b¯ and bcb¯c¯ structures which may be experimentally prominent are discussed. On the other hand, the fully-heavy S-wave tetraquark production at hadron colliders is investigated and their cross sections are obtained.

Fully-heavy tetraquark spectra and production at hadron colliders