 2021

Source paper: www.whatdotheyknow.com/request/oxford_physics_past_papers_2/response/2340696/attach/9/Physics%20Papers%202020.pdf?cookie_passthrough=1

Official standalone paper: mmathphys.physics.ox.ac.uk/sites/default/files/mmathphys/documents/media/aqft_2021.pdf

Use natural units, the Minkowski metric $g=\mathrm{diag}(1,-1,-1,-1)$ and the Feynman i-epsilon prescription. In question 1 use dimensional regularization with $d=4-2ϵ$ and write $C_{ϵ}=1/(16{\pi }^2ϵ)$; in the alternative convention $d=4-ϵ$, replace $C_{ϵ}$ by $1/(8{\pi }^2ϵ)$. Only ultraviolet poles are retained there. Figure 1 is unreadable in the released source: the corresponding specific gaps are marked below. All other parts have complete derivations.