ON THE MET BALL FLOOR: Anna Wintour may have reeled in Jennifer Lopez as the musical performer at the upcoming Costume Institute Gala on May 7, sources tell WWD. The “American Idol” judge, who is on the cover of the April issue of Vogue, has been a regular attendee of the benefit. Entertainment in recent years has included Florence + the Machine, Lady Gaga, Rihanna and Kanye West. This year’s gala is hosted by Miuccia Prada, Jeff Bezos, Carey Mulligan and Anna Wintour, in celebration of the Elsa Schiaparelli and Miuccia Prada exhibition. A spokeswoman from Vogue, however, denied that Lopez would perform.