Challenging exclusive top quark pair production at low and high luminosity LHC

The elastic production of top quark pairs in pp collisions at low and high luminosity regimes is investigated in detail. We extend the study performed in [V. P. Goncalves et al., Phys. Rev. D 102, 074014 (2020)] which has demonstrated that the sum of two semiexclusive (tt) over bar production modes, namely in photon-Pomeron (gamma P) and Pomeron-Pomeron (PP) interactions, can be experimentally measured when the (tt) over bar system decays semileptonically, (tt) over bar jjblv(l)(b) over bar, both forward protons are tagged and a low amount of pileup is present. In this study we focus on separating individual channels and a special attention is paid to the situation at high-luminosity LHC environment. We observe that the separation of the PP and gamma gamma events is a challenging task, especially at high amounts of pile-up even with an optimistic 10 ps resolution of timing detectors. In contrast, the gamma P signal is relatively well separable from all backgrounds at low levels of pileup, allowing us to discover the elastic (tt) over bar production and probe, for the first time, the production of a top quark pair in the gamma P interactions. The diffractive photoproduction of such a complex system as the (tt) over bar pair hence can be used not only to study diffractive properties of the scattering amplitude but also to search for new physics beyond the Standard Model, and consequently to be a solid part of the physics program of forward proton detectors at LHC.