Kehagias A. (Physics Division, National Technical University of Athens, 15780 Zografou Campus, Athens, Greece) Lüst D. (Arnold-Sommerfeld-Center for Theoretical Physics, Ludwig-Maximilians-Universität, 80333 München, Germany) Lust S. (CEA, IPhT (Institut de Physique Théorique), F-91191 Gif-sur-Yvette, France)