Scattering potentials, electron spin-1/2 particle

In the following sections I will consider the question of the electron-electron interaction from the perspective of modern QED. It will be useful to consider both spin-1/2 and spin-0 particles. Sec. II deals with the relatively simple case of one-photon exchange potentials, in the context of the scattering of two point particles. However, 200 years after Coulomb one ought to have some idea about the extent to which the exchange of two photons can also be represented by an effective potential. This is discussed Sec. III. In Sec. IV I turn to the question of the connection between these potentials and the properties of bound states. 

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