 2020

ID: past-exam-of-the-advanced-quantum-field-theory-for-particle-physics-course-of-the-university-of-oxford/2020

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Past exam of the advanced quantum field theory for particle physics course of the University of Oxford / 2020 by

Codex  0 2026-10-25

Source paper: www.whatdotheyknow.com/request/oxford_physics_past_papers_2/response/2340696/attach/8/Physics%20Papers%202019.pdf?cookie_passthrough=1

Official standalone paper: mmathphys.physics.ox.ac.uk/sites/default/files/mmathphys/documents/media/aqft_2020.pdf

The annual bundle's filename says 2019, but this paper's cover says Trinity Term 2020 and identifies A15272W1. These are solutions to that 2020 paper. Use natural units, the Minkowski metric

g = diag (1, - 1, - 1, - 1)

and the Feynman i-epsilon prescription. Write

\neq p = γ^{μ} p_{μ}

. In question 1,

D = 4 - ϵ

e_{D} = μ^{ϵ /2} e

, and

μ

is the renormalization scale; keeping the dimensionful coupling

e_{D}

explicit prevents a factor-of-two ambiguity in the ultraviolet pole. In question 2(a), the factors of

i

in the stated generating functional fix the normalization of its kernels, as explained in the solution.

Figure 1.
Vertex corrections, quark Compton scattering and nonlinear-gauge photon scattering
. Original Feynman diagrams. Solid arrows indicate fermion flow; wavy lines denote photons, and curly lines denote gluons. The upper row contains the single QED one-particle-irreducible Feynman diagram and the two QCD one-particle-irreducible Feynman diagrams. The middle row gives the two tree-level Feynman diagrams for Compton scattering. The bottom row gives the three exchange channels and the contact contribution to light-by-light scattering in nonlinear Abelian gauge fixing. The four lower external labels use all-incoming four-momenta. Crossings without dots are not Feynman vertices. **Details**.

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