Norwegian producers Stargate have recruited pop stars Pink and Sia to lend their vocals to their first single, the reggae-tinged Waterfall. The hitmakers, made up of Tor Erik Hermansen and Mikkel Eriksen, have been crafting tunes for the likes of Beyonce, Katy Perry, and Rihanna for years, but they are now launching careers as recording artists in their own right after signing a deal with RCA Records.