Institution: | [1]Institut fiir Angewandte Physik, Technische Universitat Darmstadt, D-64289 Darmstadt, Germany [2]Laboratoire de Physique Th6orique URAC 13, D6partement de Physique Facult6 des Sciences, Universit6 Mohammed V-Agdal Av. Ibn Battouta, B.P. 1014-Agdal, Rabat, Morocco [3]Institute for Quantum Studies and Department of Physics Texas University, TX 77843, USA |