I have the following document:
\documentclass{beamer}
\usepackage{sansmathfonts}
\begin{document}
\begin{frame}{}
Test $ a\sigma $
\end{frame}
\end{document}
If I compile it with PDFLaTeX, I get the expected result:
However, with XeLaTeX I get the following strange result:
If I remove the line \usepackage{sansmathfonts} I get what you'd expect, both with PDFLaTeX and XeLaTeX:
(note the "serif" σ).
I've tried explicitly telling beamer to use the sans font, but that didn't change anything. Also, the problem persists if I use article and set \renewcommand{\familydefault}{\sfdefault}, so I don't think this has anything to do with beamer.



