irrelevant search results

[Radha C.]

Hello List,
 
I am having the below query
 
art_id:queryText&start=0&rows=10&sort=score desc and this should not yield
any result because art_id  contains numbers.
 
But when I execute this search , it returns more than 100 documents. the
art_id field is String in schema.xml
 
Can anyone tell me how it works. What is thw wrong in the above query.
 
Thanks,
Radha.C