[Bell, G.] Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3NP, England.
[Beneke, M.] Tech Univ Munich, Phys Dept T31, D-85748 Garching, Germany.
[Huber, T.] Univ Siegen, Nat Wissensch Tech Fak, Theoret Phys 1, D-57068 Siegen, Germany.
[Li, Xin-Qiang] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.
[Li, Xin-Qiang] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.