ABSTRACT
In the last chapter we restricted ourselves to only tree-level processes, which are the lowest order Feynman diagrams for the different processes. We shall now consider higher-order radiative corrections, which are essentially quantum corrections. Since the uncertainty principle would allow creation and annihilation of virtual particles, there will be higher order loops contributing to the different processes. The main problem with such higher-order processes are the innities. QED was accepted as a consistent theory only after these innities could be properly handled and the predictions of the theory could be tested with precision measurements [2, 3].
