% !TEX program = pdflatexmk
% !TEX parameter = -shell-escape
% Author: Izaak Neutelings (March 25)
% Instructions: To compile via command line, run the following twice
%   pdflatex -shell-escape extract/LQ$TAG.tex
\documentclass[11pt,border=4pt]{standalone}
\usepackage{feynmp-auto}
\usepackage{xcolor}
\definecolor{colvtx}{rgb}{0,.1,1} % LQ vertex (blue)
\begin{document}
\begin{fmffile}{feyngraph}
  \fmfframe(3,22)(13,15){ % padding (L,T)(R,B)
  \begin{fmfgraph*}(130,80) % dimensions (WH)
    % line style
    \fmfset{dash_len}{10} % dashes length
    \fmfset{wiggly_len}{12} % boson wavelength
    \fmfset{wiggly_slope}{65} % boson slope of waves
    % external vertices
    \fmfstraight
    \fmfleft{i2,i1}
    \fmfright{o3,o2,o1}
    \fmfshift{8 up}{o1,o2}
    \fmfshift{18 left}{o3}
    % internal vertices (exact placement)
    \fmfforce{(.22w,.50h)}{v1} % exact placement
    \fmfforce{(.62w,.50h)}{v2} % exact placement
    \fmfforce{(.78w,.86h)}{lq} % exact placement
    % incoming partons
    \fmf{gluon}{v1,i1}
    \fmf{fermion}{i2,v1}
    % s-channel
    \fmf{fermion,l.s=right,label=$q$}{v1,v2}
    % associated lepton
    \fmf{fermion}{v2,o3}
    % LQ -> lepton + quark
    \fmf{dashes,t=1.2,l.s=left,label=LQ}{v2,lq}
    \fmf{fermion}{o2,lq,o1}
    % vertex
    \fmfv{d.sh=circle,d.f=full,d.si=4,f=(0,,.1,,1),
          l=\color{colvtx}$\lambda$,l.d=6,l.a=-8}{v2}
    % labels
    \fmfv{l.a=155,l.d=4,l=$g$}{i1}
    \fmfv{l.a=-155,l.d=4,l=$q$}{i2}
    \fmfv{l.a=25,l.d=4,l=$q$}{o1}
    \fmfv{l.a=-20,l.d=4,l=\vspace{-2pt}$\ell^+$}{o2}
    \fmfv{l.a=-25,l.d=3,l=$\ell^-$}{o3}
  \end{fmfgraph*}
  } % close \fmfframe
\end{fmffile}
\end{document}