Preface F. Antinori, S. Bass, A. de Falco, C. Kuhn, M. Nardi, T. Peitzmann, T. Ullrich, J. Velkovska and U.A. Wiedemann Eur. Phys. J. C, 49 1 (2007) 1 Published online: 06 January 2007 DOI: 10.1140/epjc/s10052-006-0190-6