  In this thesis we consider four dimensional N=2 superconformal field
theories, in presence of line defects such as Wilson loops. In this set up,
using supersymmetric localization, we compute many observables, such as the
vacuum expectation value of the Wilson loop, correlation functions with chiral
operators and the emitted radiation of the charged particle moving along the
Wilson loop trajectory. These results are achieved by exploiting the localized
matrix model on a four sphere, and checked against a perturbative computation
on the flat space in N=1 superspace formalism, up to four loops in perturbation
theory.
