Infrared behavior of interacting bosons at zero temperature
  We review the infrared behavior of interacting bosons at zero temperature. After a brief discussion of the Bogoliubov approximation and the breakdown of perturbation theory due to infrared divergences, we show how the non-perturbative renormalization group enables to obtain the exact infrared behavior of the correlation functions. 
N. Dupuis
cond-mat.quant-gas