22. A query translation system comprising: a statistical machine translation system including a decoder which receives a source query in a source language and outputs a set of candidate translations in a target language using biphrases extracted from a biphrase library, each of the candidate translations being a translation of the same source query; and a reranking component which outputs a target query in the target language based on at least one of the candidate translations, the reranking component extracting features of each of the candidate translations and computing a function in which the extracted features are weighted by feature weights, the weights having been learned on features of each of a set of translated queries generated by translation of an original query into the target language and a measure of information retrieval performance of each the translated queries from a collection of domain-specific documents in which documents in the collection are annotated based on relevance to original queries, for each original query in a set of original queries, at least one of the features comprising a domain-specific feature; and a processor which implements the reranking component.
22. A query translation system comprising: a statistical machine translation system including a decoder which receives a source query in a source language and outputs a set of candidate translations in a target language using biphrases extracted from a biphrase library, each of the candidate translations being a translation of the same source query; and a reranking component which outputs a target query in the target language based on at least one of the candidate translations, the reranking component extracting features of each of the candidate translations and computing a function in which the extracted features are weighted by feature weights, the weights having been learned on features of each of a set of translated queries generated by translation of an original query into the target language and a measure of information retrieval performance of each the translated queries from a collection of domain-specific documents in which documents in the collection are annotated based on relevance to original queries, for each original query in a set of original queries, at least one of the features comprising a domain-specific feature; and a processor which implements the reranking component. 24. The query translation system of claim 22 , wherein the decoder comprises a phrase-based statistical machine translation system.