After an intense months-long search, Warner Bros. has chosen Ryan Reynolds to play the title character in “Green Lantern,” the studio’s live-action movie based on the DC Comics hero. Reynolds and his representatives entered negotiations for the part Friday, after the studio held two rounds of screen tests for the actor, Bradley Cooper and Jared Leto. Justin Timberlake also did a screen test. The film is being directed by Martin Campbell and produced by Donald De Line and Greg Berlanti. One reason for the lengthy search process was that De Line, Campbell and the studio each had a different favorite among the finalists, making it difficult to come to a consensus.