Photon-fusion production of spin-even bound states at hadron colliders*

The cross sections for the production of scalar, pseudoscalar, and tensor mesons, as well as of bound spin-even systems formed by pairs of opposite-charge leptons or hadrons, are estimated for photon-photon fusion processes in ultraperipheral collisions (UPCs) of proton-proton, proton-nucleus, and nucleus-nucleus at the  RHIC, LHC and FCC colliders.

The UPC cross sections are computed in the equivalent photon approximation with realistic photon fluxes from the charged form factors of proton, lead, and gold ions. The production of three types of spin-even onium systems are considered: quarkonium (spin even meson resonances),  leptonium (positronium, dimuonium, and ditauonium), and hadronium QED atoms (pionium, kaonium, protonium, and D-onium) states.