NEW YORK/LONDON (Reuters) – Carlyle Group LP (CG.O) said on Wednesday its second-quarter earnings doubled from a year earlier as one of its European buyout funds started paying performance fees, highlighting the growth potential of its private equity business in Europe. While two U.S. buyout funds accounted for more than half of all of Carlyle’s performance fees in the quarter, the Washington, D.C.-based private equity firm said its third European buyout fund was now also a contributor. “Europe and Japan are both priced at about 20 percent lower than the United States.