% !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$TAG.tex
\documentclass[11pt,border=4pt]{standalone}
\usepackage{feynmp-auto}
\begin{document}
\begin{fmffile}{feyngraph}
  \fmfframe(-10,12)(16,12){ % padding (L,T)(R,B)
  \begin{fmfgraph*}(115,84) % dimensions (WH)
    % line style
    \fmfset{wiggly_len}{12} % boson wavelength
    \fmfset{wiggly_slope}{65} % boson slope of waves
    % external vertices
    \fmfleft{i2,i1}
    \fmfright{o2,c2,c1,o1}
    \fmfshift{2 up}{c1,o1}
    \fmfshift{2 down}{c2,o2}
    % external vertices (exact placement)
    \fmfforce{vloc(__c1)+(-.14w, .00h)}{z} % exact placement
    \fmfforce{vloc(__c1)+( .06w, .11h)}{l1} % exact placement
    \fmfforce{vloc(__c1)+( .06w,-.14h)}{l2} % exact placement
    % skeleton
    \fmf{fermion}{i1,v1,o1}
    \fmf{gluon}{i2,v2}
    \fmf{fermion}{o2,v2}
    \fmf{phantom,t=0.25}{v1,v2} % pull Vqq vertices together
    \fmf{phantom,t=0.50}{v1,i1,i2,v2} % pull Vqq vertices to left
    \fmffreeze
    % VV -> Z
    \fmf{boson,t=2.6}{w1,v1}
    \fmf{fermion,t=2.6}{v2,w2}
    \fmf{boson,t=2.0,l.s=right,l.d=4,label=W$^-$}{w1,w2} % t-channel
    \fmf{phantom}{w1,c1}
    \fmf{fermion}{w2,c2} % top quark
    \fmffreeze
    % Z -> ll
    \fmf{boson,t=1.2,label=Z,l.s=left,l.d=5}{w1,z} % Z boson
    \fmf{fermion}{l2,z,l1} % decay
    %%%% coupling
    %%%\fmfv{d.sh=circle,d.f=full,d.si=4,f=(1,,0,,0)}{w2}
    % labels
    \fmfv{l.a=158,l.d=5,l=$q$}{i1}
    \fmfv{l.a=-158,l.d=5,l=$g$}{i2}
    \fmfv{l.a=22,l.d=5,l=$q'$}{o1}
    \fmfv{l.a=25,l.d=4,l=$\ell^-$}{l1}
    \fmfv{l.a=-20,l.d=4,l=$\ell^+$}{l2}
    \fmfv{l.a=-20,l.d=4,l=t}{c2}
    \fmfv{l.a=-22,l.d=5,l=$\overline{\mathrm{b}}$}{o2}
  \end{fmfgraph*}
  } % close \fmfframe
\end{fmffile}
\end{document}