The influence of interaction between quasiparticles on parametric   resonance process in Bose-Einstein condensates
  We analyze the uniform system of weakly interacting bosonic gas undergoing periodic oscillation of interaction constant. This, within Bogoliubov approximation, leads to creation of atom pairs with well defined opposite velocities. We show how interaction between quasiparticles, omitted in the Bogoliubov approximation, significantly changes the atom pair creation process and properties of scattered atoms. 
Pawe{\l} Zi\'n and Maciej Pylak
cond-mat.quant-gas