1. A method of query processing based on normalized search terms, the method comprising: responsive to receiving a query, generating a normalized search term for a concept in the query based on a first language model, of a plurality of language models each having a predefined association with a respective concept; modifying the query to include the normalized search term; executing the modified query against an indexed corpus of evidence including a first item of evidence; and upon determining, by operation of one or more computer processors, that the first item of evidence includes the normalized search term, returning the first item of evidence as responsive to the query.