When I manually create a BooleanQuery, as shown below, the resulting FullTextQuery returns a result size of zero even though there should be at least one matching result. However, if I use the MultiFieldQueryParser to create a query using the same criteria, the expected results are returned.

Based on the code snippets below, does anyone see what could be wrong?

There is a lot of code missing in your example, but here is a guess.
A term query does not apply any analyzers, but the query parser does. Depending how your search criteria look that might explain the difference. For example the query parser would lowercase all search terms, whereas in your term query capital letters would be preserves and searched for.

--Hardy

Your guess was correct; the case where I was using the MultiFieldQueryParser (and thus a standard analyzer) the query was changed to lowercase, whereas in the BooleanQuery the search terms where left 'as is.'

Is there a way to have the BooleanQuery or the TermQuery apply an analyzer?

Thanks.

Afaik, there is not way to apply an analyzer to a TermQuery.

that's right, what I usually do is to invoke the Analyzer directly, and from the several tokens which it returns you use them to combine in a BooleanQuery