Exclusive photoproduction of vector toponium within the color dipole picture

The exclusive photoproduction of the toponium vector meson (${\psi }_t$) is investigated within the color dipole model. The overlap function between the light-cone wave function of the vector toponium state and the photon wave function is estimated using the Boosted Gaussian approach. Considering the dominance of small dipoles, the dipole-proton scattering amplitude is estimated in terms of parton distribution functions, and predictions for the photoproduction cross-section in the energy range of the proposed Large Hadron electron Collider (LHeC) are presented. Moreover, the cross-sections and rapidity distributions for the exclusive ${\psi }_t$ photoproduction in ultraperipheral proton-proton and proton - nucleus collisions at the Large Hadron Collider (LHC) and Future Circular Collider (FCC) energies are calculated. We find that exclusive ${\psi }_t$ photoproduction is, in principle, feasible in ultraperipheral $pp$ collisions at the FCC-hh.