New Force Mediators and Their Impact on Exotic Atoms

This thesis investigates the impact of new light force mediators — such as axion-like particles and spin-one gauge bosons — on the structure and spectroscopy of exotic atoms. The first part develops the theoretical framework, deriving the effective interactions between kaons, nucleons, and possible new mediators, and computing the resulting corrections to the atomic levels. The second part examines these effects using data from the SIDDHARTA-2 experiments on kaonic atoms, and extracts bounds on mediator masses and couplings. The results yield new constraints on light-force scenarios and highlight the potential of exotic-atom spectroscopy as a probe of physics beyond the standard model.