Measurements of photon induced processes in CMS and forward proton detection at the LHC

High energy photon induced processes at the CERN Large Hadron Collider (LHC) constitutes a unique testing ground for physics within and beyond the Standard Model of Elementary Particles. Colliding protons can interact by the exchange of one or two high energy photons, leading to very clean final state topologies. Several issues related to the study of photon interactions at the LHC are addressed in this Thesis. The detection of forward scattered protons, after the photon exchange, requires near-beam detectors. Developments of edgeless sensor prototypes have been realised as possible solutions for such an application. A proper design of these detectors has required developing a dedicated simulator (Hector) for the transport of charged particles particles in beamlines. Finally, the analyses of detection in the CMS experiment of the photon-induced exclusive production of lepton pairs are presented. In view of application early from the LHC start-up, in particular for the absolute luminosity measurement – the fundamental parameter of the LHC.