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14Dyson–Schwinger Equation
14.1Classification of Feynman Diagrams
14.2Basic building blocks of QED
15Regularization of Feynman Diagrams
15.1Pauli–Villars and dimensional regularization
15.1.2Photon vacuum polarization
16.1The principles of renormalization
16.2.1Fermion 2-point function
16.3Ward–Takahashi Identity and overlapping divergences
16.41-loop renormalization in QED
16.5Composite operators and Wilson expansion
16.6Criteria for renormalizability
16.8Bogoliubov’s recursion formula
16.10Dispersion relations: a brief view
17Broken Scale Invariance and Callan–Symanzik Equation
17.2Unrenormalized Ward identities of broken scale invariance
17.3Broken scale invariance and renormalized Ward identities
17.5Solution of CS equation in the deep euclidean region
17.6Asymptotic behaviour of r and zeros of the β-function
17.7Perturbative calculation of β(g) and γ(g) in ϕ4 theory
17.8QED β-function and anomalous dimension
17.9QED β-function and leading log summation
17.10Infrared fix point of QED and screening of charge
18.1The Renormalization Group equation
18.2Asymptotic solution of RG equation
19Spontaneous Symmetry Breaking
19.2More about spontaneous symmetry breaking
19.4Realization of Goldstone Theorem in QFT
20.1Generating functional of proper functions
