NEW YORK, May 4 (Xinhua) -- Picasso on Tuesday claimed back the world record for artwork auction, just three months after conceding the record to an Italian sculptor. Pablo Picasso\'s \"Nude, Green Leaves and Bust\" garnered over 106 million U.S. dollars at Christie\'s, beating the 104.3 million-dollar mark set in early February by Alberto Giacometti\'s \"Walking Man One\" at Sotheby\'s in London. Art experts estimated that the Picasso canvas, depicting the Spanish maestro\'s mistress...