[xsl] Ampersand in CDATA

Hi, I have the following XSL template using the PHP5 XSLT 1.0 processor:

<xsl:template match="/">
<![CDATA[ & ]]>
</xsl:template>

This is the PHP code I use to execute the transformation:

  // Load XSL file
  $xsl_dom = new DOMDocument();
  $xsl_dom->load($xsl_filename);

  // Apply XSL
  $xsl = new XSLTProcessor();
  $xsl->importStyleSheet($xsl_dom);
  echo $xsl->transformToXML($xml_dom);

I expect it to output just an ampersand by itself, but instead, I'm
getting "&amp;". What's going on?

-Geoffrey Lee