ABSTRACT
Quantum Electrodynamics (QED) is one of three parts of the Standard Model of Particle Physics, the other two parts being the theories of the strong and weak interactions. The basic structure and foundations of QED are incorporated into the other parts of the Standard Model, and so what we learn from QED will be useful when it comes to learning about the other parts of the Standard Model. It is a dimensionless number that characterizes the strength of the electromagnetic coupling. The next simplest process is that of the scattering of a particle off of its own antiparticle. In order to finish any of these calculations we would have to specify all of the initial and final spins in the problem, insert the corresponding free-particle solutions into the expression and then integrate over the solid angle to get the cross-section.
