 2020

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

The cover establishes Hilary Term 2020 despite the source bundle's 2019 filename. Use $\hslash =c=1$, the Minkowski metric $\eta =\mathrm{diag}(1,-1,-1,-1)$, and $/p={\gamma }^{\mu }{p}_{\mu }$ for Feynman slash notation. In question 1, the repeated species index in the Yukawa interaction is summed over $i=1,2$. The spatial mode expansions in question 2 are at a fixed time.