Density-dependent modifications of the transition spectrum of an atom located inside cold atomic ensemble

On the basis of general theoretical results developed in our group previously [Sokolov I M et al 2011 J. Exp. Theor. Phys. 112 246], the transition spectrum of a single atom inside cold atomic ensemble is analyzed under conditions when the averaged interatomic separation is less than or comparable with the wavelength of resonant radiation. Density-dependent shifts of resonance as well as distortion of the spectral shape of the atomic transition are investigated