Quantum Electrodynamics and Many-body Perturbation Theory

1 Quantum Electrodynamics and Many-body Perturbation Theory. - In his 

In his work, Goldstone70 introduced the graphical techniques into many-body physics making use of Feynman-like diagrams. However, interactions were taken to be instantaneous and the effects of relativity were ignored. In recent years, the growing interest in the treatment of relativistic and quantum electrodynamic effects in atoms and molecules is necessitating the reintroduc- 

Goldstone used a second quantized particle-hole formalism based on an arbitrary choice of vacuum state. The interaction representation, which is intermediate between the Schrddinger and Heisenberg pictures, was employed and the energy was evaluated by the Gell-Mann-Low formalism78 with Hamiltonian 

A more symmetrical treatment was presented by Sucher80 which allows the interacting state to evolve to t = +oo 

This S matrix approach leads to the modified Gell-Mann-Low formula for the energy shift 

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