<html><head><meta name="color-scheme" content="light dark"></head><body><pre style="word-wrap: break-word; white-space: pre-wrap;">%% 
%%  The LaTeX Graphics Companion, 2ed (first printing May 2007)
%% 
%%  Example 8-4-21 on page 572.
%% 
%%  Copyright (C) 2007 Michel Goossens, Frank Mittelbach, Denis Roegel, Sebastian Rahtz, Herbert Vo\ss 
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 

\documentclass{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{111.83385pt}
\AtEndDocument{\end{fmffile}}
  \AtBeginDocument{\begin{fmffile}{ftmp}}
\StartShownPreambleCommands
\usepackage{feynmp}
\StopShownPreambleCommands
\begin{document}
\begin{fmfgraph*}(90,70)
 \fmfleft{i1,i2}   \fmfright{o1}
 \fmf{photon,tension=4}{i1,v1} \fmf{photon,tension=4}{i2,v3}
 \fmf{photon,tension=4}{v2,o1}
 \fmfcyclen{fermion,tension=1}{v}{3}
 \fmf{fermion,tension=1,left=1.4/3}{v1,v3}
 \fmf{fermion,tension=1,left=2/3}{v3,v2}
 \fmf{fermion,tension=1,left=2/3}{v2,v1}
\end{fmfgraph*}
\end{document}
</pre></body></html>