Displaying diagrams

Lets say we've generated some diagrams, like so:

SetOptions[$Output, PageWidth -> 65];
$HistoryLength = 2;

Get["alibrary.m"];
Get[$Apath <> "/amodel-qcd.m"];

diagrams = Diagrams[{"A"}, {"A"}, 2];

Normally the diagrams would now be passed into Amplitude to apply Feyman rules to them; there are however two reasons to additionally convert them into a viewable form: to debug the Feynman rules and to prepare publications.

Quick & dirty diagram viewing

There are two ways to view the obtained diagrams. One way is by producing .dot files for them, using graphviz to convert those into PDFs, and importing the PDFs into Mathematica. This achieves a quick and dirty view of the diagram, suitable for debugging:

diagrams // Map[DiagramViz]

Note that the result of DiagramViz is a Graphics[] object, and the Mathematica GUI frontend is needed to see it.

Exporting diagrams to LaTeX

The other objective is to prepare publication-quality LaTeX renderings of the diagrams. To that end, we have found it best to use the TikZ library in combination with the TikZiT editor. To use this combination, first export any diagram to a .tikz (LaTeX) file:

MkFile["diagram.tikz", DiagramToTikZ[diagrams[[1]]]];

Then edit it with TikZiT by running tikzit diagram.tikz. Make sure to load the all.tiksztyles style file that comes with alibrary to be able to preview the diagrams insize TikZiT.

Once you're done, you can include diagram.tikz into any LaTeX source (in text or in a formula) to get a picture of the diagram. A minimal example would be:

\documentclass{article}
\input{all.tikzdefs}
\input{all.tikzstyles}
\begin{document}
  \input{diagram.tikz}
\end{document}

Note that both all.tikzdefs and all.tikzstyles are required for this to work.

The result might looks like this:

\begin{tikzpicture} \begin{pgfonlayer}{nodelayer} \node [style=none] (-1) at (-1.5, 0) {}; \node [style=none] (-2) at (1.5, 0) {}; \node [style=dot] (1) at (-1, 0) {}; \node [style=dot] (2) at (1, 0) {}; \node [style=dot] (3) at (0, 1) {}; \node [style=dot] (4) at (0, -1) {}; \end{pgfonlayer} \begin{pgfonlayer}{edgelayer} \draw [style=incoming vector] (-1.center) to (1); \draw [style=outgoing vector] (2) to (-2.center); \draw [style=fermion] (3) to (1); \draw [style=fermion] (1) to (4); \draw [style=fermion] (2) to (3); \draw [style=fermion] (4) to (2); \draw [style=gluon] (4) to (3); \end{pgfonlayer} \end{tikzpicture}