1. Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna 141980, Russia
2. Research Center of Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047, Japan
3. Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan