1. A system, comprising: one or more computer processors; and a memory containing a program, which, when executed by the one or more computer processors, performs an operation for query processing based on normalized search terms, the operation 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 the indexed corpus of evidence, where the corpus of evidence is indexed based on the plurality of language models to include a set of normalized terms for each respective item of evidence in the corpus, wherein the indexed corpus of evidence includes a first item of evidence used to support a first candidate answer, of a plurality of candidate answers; and upon determining that the set of normalized terms for the first item of evidence includes the normalized search term, returning the first candidate answer as responsive to the query.