Film Music Reporter has confirmed that Christophe Beck is set to score ANT-MAN.
Per Film Music Reporter: "Beck has previously collaborated with Peyton on 2000’s Bring It On, which was the composer’s first major hit film credit. Ant-Man is set to be released on July 17, 2015 by Walt Disney Pictures. For updates on the film, visit the official movie website."
Source: Film Music Reporter.