The National Football League doesn’t usually pay the act that performs at halftime during the Super Bowl. But in a twist this year, the league has asked artists under consideration for the high-profile gig to pay to play, according to people familiar with the matter. The NFL has narrowed down the list of potential performers for the 2015 Super Bowl to three candidates: Rihanna, Katy Perry, and Coldplay, these people said. While notifying the artists’ camps of their candidacy, league representatives also asked at least some of the acts if they would be willing to contribute a portion of their post-Super Bowl tour income to the league, or if they would make some other type of financial contribution, in exchange for the halftime gig. The pay-to-play suggestion got a chilly reception from the candidates’ representatives, these people said.