On a theory of light scattering from a Bose-Einstein condensate
  We consider a quantum theory of elastic light scattering from macroscopic atomic sample existing in the Bose-Einstein condensate (BEC) phase. Following to the second quantized formalism we introduce a set of coupled and closed diagram equations for the polariton propagator contributing to the $T$ -matrix and scattering amplitude. Our approach allows to follow important density correction to the quasi-energy structure caused by static interaction and radiation losses associated with incoherent scattering in the case of near resonance excitation. 
Victoria Ezhova, Leonid Gerasimov, Dmitriy Kupriyanov
quant-ph cond-mat.quant-gas physics.atom-ph