 2018

Source paper: www.whatdotheyknow.com/request/oxford_physics_past_papers_2/response/2340696/attach/6/Physics%20Papers%202017.pdf?cookie_passthrough=1

The dated cover establishes Trinity Term 2018, despite the containing bundle's 2017 filename. Use natural units, the Minkowski metric $g=\mathrm{diag}(1,-1,-1,-1)$ and the Feynman i-epsilon prescription. In question 1(a), $D=4-ϵ$ and $e_D={\mu }^{ϵ/2}e$. The supplied transverse photon propagator selects Landau gauge within the Lorenz-gauge family. In question 2(a), distinguish the kernels in the stated generating functional from time-ordered Wick contractions, as explained below.