% !TEX program = pdflatexmk
% !TEX parameter = -shell-escape
% Author: Izaak Neutelings (September 24)
% Instructions: To compile via command line, run the following twice
%   pdflatex -shell-escape extract/basic_QED$TAG.tex
\documentclass[11pt,border=4pt]{standalone}
\usepackage{feynmp-auto}
\begin{document}
\begin{fmffile}{feyngraph}
  \fmfframe(-2,12)(0,14){ % padding (L,T)(R,B)
  \begin{fmfgraph*}(100,60) % dimensions (WH)
    % external vertices
    \fmfleft{i2,i1}
    \fmfright{o2,o1}
    % main
    \fmf{fermion}{i1,v1,o1}
    \fmf{boson,tension=0.7,label.side=right,label=$\gamma$}{v1,v2} % t-channel
    \fmf{fermion}{o2,v2,i2}
    % labels
    \fmflabel{e$^-$}{i1}
    \fmflabel{e$^+$}{i2}
    \fmflabel{e$^-$}{o1}
    \fmflabel{e$^+$}{o2}
  \end{fmfgraph*}
  } % close \fmfframe
\end{fmffile}
\end{document}