% !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/VLQ_VLL$TAG.tex
\documentclass[11pt,border=4pt]{standalone}
\usepackage{feynmp-auto}
\usepackage{xcolor}
\usepackage{scalerel}
\newcommand{\mylbrace}[2]{\vspace{#2pt}\hspace{4pt}\scaleleftright[\dimexpr6pt+#1\dimexpr0.11pt]{\lbrace}{\rule[\dimexpr2pt-#1\dimexpr0.5pt]{-4pt}{#1pt}}{.}}
\newcommand{\myrbrace}[2]{\vspace{#2pt}\scaleleftright[\dimexpr6pt+#1\dimexpr0.11pt]{.}{\rule[\dimexpr2pt-#1\dimexpr0.5pt]{-4pt}{#1pt}}{\rbrace}\hspace{2pt}}
\definecolor{colVLQ}{rgb}{.5,0,.7} % VLQ (purple)
\begin{document}
\begin{fmffile}{feyngraph}
  \fmfframe(1,16)(8,18){ % padding (L,T)(R,B)
  \begin{fmfgraph*}(110,75) % canvas (W,H)
    % line style
    \fmfset{wiggly_len}{12} % boson wavelength
    \fmfset{wiggly_slope}{65} % boson slope of waves
    % external vertices
    \fmfstraight
    \fmfleft{i2,i1} % incoming vertices
    \fmfright{o2,o1} % outgoing vertices
    % main process
    \fmf{gluon}{i2,v1,i1} % incoming particles
    \fmf{fermion,f=(.5,,0,,.7)}{o2,v2,o1} % outgoing particles
    \fmf{gluon,t=1.1}{v2,v1} % s-channel
    % labels
    \fmfv{l.d=5,l.a=156,l=g}{i1}
    \fmfv{l.d=5,l.a=-156,l=g}{i2}
    \fmfv{l.d=5,l.a=25,l=\color{colVLQ} Q}{o1}
    \fmfv{l.d=5,l.a=-25,l=\color{colVLQ}$\overline{\mathrm{Q}}$}{o2}
  \end{fmfgraph*}
  } % close \fmfframe
\end{fmffile}
\end{document}