Gain-assisted superluminal light propagation through a Bose-Einstein condensate cavity system S. Hamide Kazemi, S. Ghanbari and M. Mahmoudi Eur. Phys. J. D, 70 1 (2016) 1 Published online: 12 January 2016 DOI: 10.1140/epjd/e2015-60506-8