Study of light-by-light scattering with the ATLAS Forward Proton (AFP) Detector at CERN

This thesis deals with the study of light-by-light scattering in the Standard Model of particle physics and in its extension predicted by Peccei-Quinn theory. It compares photon induced lepton pair productions with the hypothetical axion-like particle production, which could mediate light-by-light scattering, based on Monte Carlo simulations. Furthermore, it applies non-parametric Bayesian approach, the Gaussian Process, to model smooth background based on the invariant mass of scattered diphotons observed in ultraperipheral collisions with the ATLAS experiment. The estimated background is then used with simulated signal injection representing production of axion-like particle to determine the detection probability.