XPATH to select tag immediately following another tag with no text

So here's my next query. Imagine the following XML:

<par>This is a <xref>Link</xref> to something else.</par>
<par><xref>Link</xref> to something else.</par>

I am looking to differentiate between the 2 xref tags. The only difference is whether they are treated as a word end. In the first, it SHOULD be; in the second, it SHOULDN'T be. I therefore need a parser rule that can determine that there is no text between the parent and sibling.

Unfortunately, I am having no luck and hoping someone can help with this special case.