% !TEX program = pdflatexmk
% !TEX parameter = -shell-escape
% Author: Izaak Neutelings (December 24)
% Instructions: To compile via command line, run the following twice
%   pdflatex -shell-escape extract/singletop$TAG.tex
\documentclass[11pt,border=4pt]{standalone}
\usepackage{feynmp-auto}
\begin{document}
\begin{fmffile}{feyngraph}
  \fmfframe(-10,10)(11,10){ % padding (L,T)(R,B)
  \begin{fmfgraph*}(125,70) % dimensions (WH)
    % line style
    \fmfset{wiggly_len}{12} % boson wavelength
    \fmfset{wiggly_slope}{65} % boson slope of waves
    % external vertices
    \fmfleft{i2,i1}
    \fmfright{o2,w,o1}
    \fmfshift{5 left}{w}
    \fmfshift{6 right}{o2}
    % internal vertices (exact placement)
    \fmfforce{(.43w,.78h)}{v1} % exact placement
    \fmfforce{(.43w,.22h)}{v2} % exact placement
    \fmfforce{(.70w,.22h)}{vw} % exact placement
    % main
    \fmf{gluon,t=1.3}{v1,i1}
    \fmf{gluon,t=1.3}{i2,v2}
    \fmf{fermion,t=0.7,l.s=left,label=t}{v2,v1} % t-channel
    \fmf{fermion}{v1,o1} % top quark
    \fmf{fermion}{o2,vw,v2}
    \fmf{boson,t=0}{vw,w} % W boson
    % labels
    \fmfv{l.a=158,l.d=6,l=$g$}{i1}
    \fmfv{l.a=-158,l.d=6,l=$g$}{i2}
    \fmfv{l.a=22,l.d=6,l=t}{o1}
    \fmfv{l.a=-22,l.d=6,l=$\overline{\mathrm{b}}$}{o2}
    \fmfv{l.a=26,l.d=4,l=W$^+$}{w}
  \end{fmfgraph*}
  } % close \fmfframe
\end{fmffile}
\end{document}