% !TEX program = pdflatexmk
% !TEX parameter = -shell-escape
% Author: Izaak Neutelings (September 25)
% Instructions: To compile via command line, run the following twice
%   pdflatex -shell-escape extract/ttbar$TAG.tex
\documentclass[11pt,border=4pt]{standalone}
\usepackage{feynmp-auto}
\begin{document}
\begin{fmffile}{feyngraph}
  \fmfframe(-6,14)(34,16){ % padding (L,T)(R,B)
  \begin{fmfgraph*}(110,150) % dimensions (WH)
    % line style
    \fmfset{wiggly_len}{12} % boson wavelength
    \fmfset{wiggly_slope}{65} % boson slope of waves
    \fmfset{arrow_len}{3.6mm}
    % external vertices
    \fmfstraight
    \fmfleft{i} % add dummies 'd' for spacing
    \fmfright{o6,o5,o4,o3,o2,o1}
    \fmfshift{2 up}{i1}
    \fmfshift{2 down}{i2}
    % ttbar
    \fmf{fermion,l.s=left,label={$\mathrm{t}$}}{i,v1}
    \fmf{fermion,l.s=left,label={$\overline{\mathrm{t}}$}}{v2,i}
    % bbbar
    \fmf{fermion,t=0.6}{v1,o1}
    \fmf{fermion,t=0.6}{o6,v2}
    \fmffreeze
    % W -> qq / lnu
    \fmf{boson,t=1.2,label=W$^+$,l.d=5,l.s=right}{v1,w1} % W boson
    \fmf{boson,t=1.2,label=W$^-$,l.d=5,l.s=left}{v2,w2} % W boson
    \fmf{fermion,t=1}{o3,w1,o2} % W decay
    \fmf{fermion,t=1}{o5,w2,o4} % W decay
    \fmf{phantom,t=0.05}{w1,w2} % pull decay vertices together
    % labels
    \fmfv{l.a=25,l.d=5,l=b}{o1}
    \fmfv{l.a=-25,l.d=5,l=$\overline{\mathrm{b}}$}{o6}
    \fmfv{l.a=20,l.d=6,l=\makebox[3.1mm][l]{$q$} / $\nu_\ell$}{o2}
    \fmfv{l.a=-20,l.d=6,l=\makebox[3.1mm][l]{$\overline{q}'$} / $\ell^+$}{o3}
    \fmfv{l.a=20,l.d=6,l=\makebox[3.1mm][l]{$\ell^-$} / $q$}{o4}
    \fmfv{l.a=-20,l.d=6,l=\makebox[3.1mm][l]{$\overline{\nu}_\ell$} / $\overline{q}'$}{o5}
  \end{fmfgraph*}
  } % close \fmfframe
\end{fmffile}
\end{document}