[xsl] parser error with CDATA string '&a'

["Werner Remmers" <w.remmers@xxxxxx>]

Hi all,

I'm trying to transform an XML document that contains elements like this 
one:

<url_download>www.example.com?var=1&a=3</url_download>

But this is what I get from Saxon 9:

SXXP0003: Error reported by XML parser: The reference to entity "a" must end 
with the ';' delimiter.

I already tried to wrap the content of the element in CDATA, like this:

<url_download><![CDATA[www.example.com?var=1&a=3]]></url_download>

Unfortunately this doesn't work too.

Thanks in advance!
Werner

I am using:
XSLT 2.0
Saxon 9