Producer: George Drakoulias - Artist: Katy Perry - Vocal Producer: Bart Schoudel - Mixer: Martin Pradler - Vocalist: Katy Perry - Vocalist: Rachael Findlen - Background Vocalist: Bart Schoudel - Keyboards: Patrick Warren - Strings: Patrick Warren - Viola: Daphne Chen - Violin: Daphne Chen - Guitar: Mason Stoops - Bass: Lance Morrison - Drums: Jake Reed - Percussion: Jake Reed - Trumpet: Gabriel Johnson - Trumpet: Stewart Cole - Aerophones: Vincent Henry - A&R Admin: Liz Isik - Recording Engineer: Patrick Warren - Vocal Engineer: Rachael Findlen - Mastering Engineer: Martin Pradler - Composer/Author: John Lennon