% !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/HNL$TAG.tex
\documentclass[11pt,border=4pt]{standalone}
\usepackage{feynmp-auto}
\usepackage{xcolor}
\usepackage{scalerel}
\newcommand{\mylbrace}[2]{\vspace{#2pt}\hspace{4pt}\scaleleftright[\dimexpr6pt+#1\dimexpr0.11pt]{\lbrace}{\rule[\dimexpr2pt-#1\dimexpr0.5pt]{-4pt}{#1pt}}{.}}
\newcommand{\myrbrace}[2]{\vspace{#2pt}\scaleleftright[\dimexpr6pt+#1\dimexpr0.11pt]{.}{\rule[\dimexpr2pt-#1\dimexpr0.5pt]{-4pt}{#1pt}}{\rbrace}\hspace{2pt}}
\definecolor{colHNL}{rgb}{.1,.5,.1} % HNL (green)
\begin{document}
\begin{fmffile}{feyngraph}
  \fmfframe(1,14)(11,14){ % padding (L,T)(R,B)
  \begin{fmfgraph*}(160,140) % canvas (W,H)
    % line style
    \fmfset{wiggly_len}{12} % boson wavelength
    \fmfset{wiggly_slope}{65} % boson slope of waves
    % external vertices
    \fmfstraight
    \fmfleft{d,i2,d,i1,d}
    \fmfright{o6,o5,o4,o3,o2,o1}
    \fmfshift{10 left}{o1,o6}
    \fmfshift{5 down}{i1}
    \fmfshift{5 up}{i2}
    % qq -> Z & skeleton
    \fmf{fermion,t=1.5}{i1,v1,i2}
    \fmf{boson,t=1.5,label=Z/$\gamma^*$,l.s=right,l.d=4}{v2,v1}
    \fmf{fermion,t=0.7}{w1,o1} % top outgoing fermion
    \fmf{fermion,t=0.7}{o6,w2} % bottom outgoing fermion
    % W decay to heavy leptons
    \fmf{fermion,t=1.1,f=(.1,,.5,,.1),label=\color{colHNL} $\Sigma^\mp$,l.d=3,l.s=left}{v2,w1} % HNL
    \fmf{fermion,t=1.1,f=(.1,,.5,,.1),label=\color{colHNL} $\Sigma^\pm$,l.d=4,l.s=left}{w2,v2} % HNL
    \fmffreeze
    % HNL decay
    \fmf{boson,t=1.2,label=Z,l.d=5,l.s=right}{w1,d1} % Z boson
    \fmf{fermion}{o2,d1,o3}
    % HCL decay
    \fmf{boson,t=1.2,label=Z,l.d=5,l.s=left}{w2,d2} % Z boson
    \fmf{fermion}{o5,d2,o4}
    % labels
    \fmfv{l.d=4,l.a=155,l=q}{i1}
    \fmfv{l.d=4,l.a=-155,l=$\overline{\mathrm{q}}$}{i2}
    \fmfv{l.d=5,l.a=25,l=$\ell^\mp$}{o1}
    \fmfv{l.d=5,l.a=20,l=q$'$}{o2}
    \fmfv{l.d=5,l.a=-15,l=$\overline{\mathrm{q}}'$}{o3}
    \fmfv{l.d=5,l.a=15,l=$\ell^\mp$}{o4}
    \fmfv{l.d=5,l.a=-15,l=$\ell^\pm$}{o5}
    \fmfv{l.d=4,l.a=-25,l=$\ell^\pm$}{o6}
  \end{fmfgraph*}
  } % close \fmfframe
\end{fmffile}
\end{document}