[1] Univ Durham, Inst Particle Phys Phenomenol, Dept Phys, Durham DH1 3HP, England
[2] Heidelberg Univ, Inst Theoret Phys, D-6900 Heidelberg, Germany
[3] Karlsruhe Inst Technol, Inst Theoret Phys, Karlsruhe, Germany
[4] CNRS, LAL, IN2P3, F-91405 Orsay, France
[5] Deutsch Elektronen Synchrotron DESY, Hamburg, Germany
[6] Rhein Westfal TH Aachen, Inst Theoret Teilchenphys & Kosmol, Aachen, Germany