% !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/higgs_decay$TAG.tex
\documentclass[11pt,border=4pt]{standalone}
\usepackage{feynmp-auto}
\usepackage{xcolor}
\definecolor{colkappaV}{rgb}{.15,.75,.15} % kappa_V (green)
\begin{document}
\begin{fmffile}{feyngraph}
  \fmfframe(5,8)(20,8){ % padding (L,T)(R,B)
  \begin{fmfgraph*}(110,50) % dimensions (WH)
    % line style
    \fmfset{wiggly_len}{12} % boson wavelength
    \fmfset{wiggly_slope}{65} % boson slope of waves
    % external vertices
    \fmfstraight
    \fmfleft{i2,i,i1}
    \fmfright{o2,o1}
    % skeleton
    \fmf{phantom,t=0.5}{v1,i1,i2,v2} % pull Wyy vertices to left
    \fmf{boson}{v1,o1}
    \fmf{boson}{v2,o2}
    \fmffreeze
    % main
    \fmf{dashes,t=2.1}{i,v} % Higgs boson
    \fmf{boson,l.s=left,label=W}{v,v1,v2,v} % triangle loop
    % Higss coupling
    \fmfv{decor.shape=circle,decor.filled=full,decor.size=4,f=(.15,,.75,,.15),
          l.d=5,l.a=115,l=\color{colkappaV}$\kappa_\mathrm{W}$\hspace{-1pt}}{v}
    % labels
    \fmflabel{h}{i}
    \fmfv{l.a=0,l.d=5,l=$\gamma$,, Z}{o1}
    \fmfv{l.a=0,l.d=5,l=$\gamma$}{o2}
  \end{fmfgraph*}
  } % close \fmfframe
\end{fmffile}
\end{document}