Examination paper for FY3464 Quantum Field Theory I

We calculated the contribution of a scalar field with mass m to the vacuum energy density ρ twice, once introducing a cutoff M in momentum space and once using

In the lectures we developed a perturbation expan- sion (in the electron-impurity scattering potential) for the impurity-averaged Matsubara single-particle Green function G(k, ip m

We represented each term in the perturbation ex- pansion for G(k, ip m ) by a Feynman diagram and established the Feynman rules for translating between the diagrams and their

We represented each term in the perturbation expansion for ¯ G(k, ip m ) by a Feynman diagram and established the Feynman rules for translating between the diagrams and their