[XeTeX] math font problem with beamer

[Horst Hohberger]

Since updating to MacTeX 2011, I have a font kerning problem when using xelatex with beamer and the fontspec package; the spacing in mathematical formulas is off, so letters collide with parentheses and text decorations. 

Here is a minimal example:

---------
%!TEX TS-program = xelatex 
%!TEX encoding = UTF-8 Unicode

\documentclass{beamer} 

\usepackage[no-math]{fontspec}
\usepackage{xunicode}
\usepackage{xltxtra}

\begin{document}
	
\begin{frame}
$f(x)$ and $y'$
\end{frame}

\end{document}
---------

When the three \usepackage commands are commented out, the spacing is fine; with the three packages, the f runs into the left parenthesis and the prime touches the letter y. 

Am I missing some option when calling the packages? Any help is appreciated!

Horst


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Dr. Horst Hohberger

Lecturer for Mathematics

University of Michigan - Shanghai Jiaotong University Joint Institute
上海交通大学密西根学院

Phone: +86 134 828 97 417
Web: http://umji.sjtu.edu.cn/personal/horst/

PGP Public Key: 
http://umji.sjtu.edu.cn/personal/horst/horst_hohberger.gpgkey

Shanghai Jiao Tong University (Minhang Campus)
Room 218, Law School Building
800 Dongchuan Road
200240 Shanghai
P. R. China