1. A method for re-ranking results of a cross-lingual search, wherein the cross-lingual search is performed using a search query of a first language to retrieve a first set of documents in the first language and a second set of documents in a second language, the method comprising: for each document of the first set and the second set of documents, computing a value of a unified ranking function which is a function of the search query and the document; and ranking the first set of documents and the second set of documents together based on the values of the unified ranking function.