We analyze the LHC prospects for measurements of the $tbar{t}$ pair produced exclusively in photon-photon or semi-exclusively in photon-Pomeron and Pomeron-Pomeron processes using protons tagged in forward proton detectors on both sides of the intera
ction point. These processes are interesting from the point of view of a possible measurement of the top quark mass and constraining models used in Beyond Standard Model physics. Focusing on the semi-leptonic channel, $tbar{t}rightarrow jjbl u_lbar{b}$, making use of the exclusive nature of the final state, together with the use of timing information provided by forward proton detectors, relevant exclusive and inclusive backgrounds are studied in detail for different luminosity (or pile-up) scenarios and found to be important for further considerations. While good prospects are found for observing the signal, the top quark mass measurement turns out not to be competitive with measurements in inclusive channels.
A phenomenological study of the isolated photon production in high energy $pp$ and $pA$ collisions at RHIC and LHC energies is performed. Using the color dipole approach we investigate the production cross section differential in the transverse momen
tum of the photon considering three different phenomenological models for the universal dipole cross section. We also present the predictions for the rapidity dependence of the ratio of $pA$ to $pp$ cross sections. As a further test of the formalism, for different energies and photon rapidites we analyse the correlation function in azimuthal angle $Deltaphi$ between the photon and a forward pion. The characteristic double-peak structure of the correlation function around $Delta phisimeq pi$ observed previously for Drell-Yan pair production is found for isolated photon emitted into the forward rapidity region which can be tested by future experiments.
