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interduck.tex

\documentclass[preview=true, border=2mm]{standalone}
\usepackage{bm} % boldmath
\usepackage{mathrsfs}
\usepackage{tikz}
\usetikzlibrary{shapes}
\usepackage{tikzducks}
\usepackage{tikz-feynman}

\definecolor{beaublue}{rgb}{0.74, 0.83, 0.9}
\definecolor{amethyst}{rgb}{0.6, 0.4, 0.8}
\definecolor{carminepink}{rgb}{0.92, 0.3, 0.26}

\newcommand{\InteractionRegionColor}{beaublue}
\newcommand{\PropColor}{carminepink}
\newcommand{\GravitonColor}{amethyst}

\begin{document}
\newsavebox{\myduck}
\sbox{\myduck}{\begin{tikzpicture}
  \duck{}
\end{tikzpicture}
}
\newcommand{\scaledduck}[1][1cm]{\resizebox{#1}{!}{\usebox{\myduck}}}
\begin{figure}
  \begin{tikzpicture}[every node/.style={draw=none, circle, fill=none,
      outer sep=1mm, inner sep=0pt}]
    \tikzfeynmanset{myprop/.style={\PropColor,fermion,edge,very thick}}
    \tikzfeynmanset{mygraviton/.style={\GravitonColor,charged boson, very thick}}
    \begin{feynman}
      % Interaction region
      \vertex[blob, ellipse, fill=\InteractionRegionColor, align=center,
      inner sep=2mm, outer sep=1mm] (m) at ( 0, 0) {Interduck \\ region};

      % Two input and one output BHs
      \vertex[label={left:$m_{1}, \bm{\chi}_{1}$}, minimum size=4mm] (a) at (-3, 1) {\scaledduck[5mm]};
      \vertex[label={left:$m_{2}, \bm{\chi}_{2}$}, minimum size=2mm] (b) at (-3,-1) {\scaledduck[3mm]};
      \vertex[label={right:$m_{f}, \bm{\chi}_{f}, \bm{v}_{f}$},
      minimum size=5mm] (c) at ( 3, 0.5) {\scaledduck[6mm]};

      % Fake vertices to make sure all GW lines have same slope
      \vertex[below = 1cm of m] (belowm1);
      \vertex[right = 5mm of belowm1] (belowm2);
      \vertex[right = 5mm of belowm2] (belowm3);

      \vertex[below right = 6mm and 9mm of belowm1] (w1);
      \vertex[below right = 6mm and 9mm of belowm2] (w2);
      \vertex[below right = 6mm and 9mm of belowm3] (w3);

      % Separate text vertex or else the vertices above get pushed
      % around, messing up the angles
      \vertex[below = 1mm of w2, align=center, rectangle, fill=none, draw=none]
      (wtext) {Duck waves\\ to $\mathscr{I}^{\scaledduck[2mm]}$};

      \diagram* {
        (a) -- [myprop] (m) -- [myprop] (c),
        (b) -- [myprop] (m),
        (belowm1) -- [mygraviton] (w1);
        (belowm2) -- [mygraviton] (w2);
        (belowm3) -- [mygraviton] (w3);
      };
    \end{feynman}
  \end{tikzpicture}
\end{figure}
\end{document}