# Using \pause with Feynman diagrams in Beamer

When using Beamer (for a presentation), Feynman diagrams (created with Feynmp-auto) don't appear to work with \pause or \uncover, the diagrams are just there from the start of the slide. However both of these commands work with text/equations so it must be something to do with the Feynman diagrams.

Here is my MWE:

\documentclass{beamer}
\mode<presentation>
{\usetheme{Warsaw}
\setbeamercovered{transparent}}
\usepackage{feynmp-auto}
\usepackage[english]{babel}
\usepackage[latin1]{inputenc}
\usepackage{times}
\usepackage[T1]{fontenc}
\usepackage{graphicx}
\begin{document}

\includegraphics[width=5cm]{complicated}
\uncover<2>{
\begin{fmffile}{Feynmanparameters}
\begin{fmfgraph*}(150,80)
\fmfleft{i1,i2}
\fmfright{o2,o3}
\fmf{fermion}{i1,v1}
\fmf{plain}{v1,v2}
\fmf{fermion}{v2,v3}
\fmf{plain}{v3,i2}
\fmf{fermion}{o2,v5}
\fmf{plain}{v5,v4}
\fmf{plain}{v4,v6}
\fmf{fermion}{v6,o3}
\fmf{photon}{v2,v4}
\fmffreeze
\fmf{photon,left=0.5,tension=0.2}{v1,v3}
\end{fmfgraph*}
\end{fmffile}}
\end{document}

• The Feynman diagrams are being generated externally, in metapost, and then imported as a graphics file, så \pause doesn't have a chance to work. – Andrew Swann Feb 16 '15 at 19:59
• I thought that might have something to do with it, is there any way to get it to work? – supercoolphysicist Feb 16 '15 at 20:58
• You could use TikZ for the graphs, it as excellent beamer integration. – MaxNoe Feb 17 '15 at 9:01

I fixed this by using the only command - I'm not sure why it worked though!

New code:

\documentclass{beamer}
\mode<presentation>
{\usetheme{Warsaw}
\setbeamercovered{transparent}}
\usepackage{feynmp-auto}
\usepackage[english]{babel}
\usepackage[latin1]{inputenc}
\usepackage{times}
\usepackage[T1]{fontenc}
\usepackage{graphicx}
\begin{document}

\includegraphics[width=5cm]{complicated}
\only<2>{
\begin{fmffile}{Feynmanparameters}
\begin{fmfgraph*}(150,80)
\fmfleft{i1,i2}
\fmfright{o2,o3}
\fmf{fermion}{i1,v1}
\fmf{plain}{v1,v2}
\fmf{fermion}{v2,v3}
\fmf{plain}{v3,i2}
\fmf{fermion}{o2,v5}
\fmf{plain}{v5,v4}
\fmf{plain}{v4,v6}
\fmf{fermion}{v6,o3}
\fmf{photon}{v2,v4}
\fmffreeze
\fmf{photon,left=0.5,tension=0.2}{v1,v3}
\end{fmfgraph*}
\end{fmffile}}
\end{frame}
\end{document}

• Can you make the answer more explicit? – egreg Feb 16 '15 at 22:32