Remarks on derivative nonlinear Schr\"odinger systems with multiple   masses
  We prove global existence of small solutions to the initial value problem for a class of cubic derivative nonlinear Schr\"odinger systems with the masses satisfying suitable non-resonance relations. The large-time asymptotics of the solutions are also shown. This work is intended to provide a counterpart of the previous paper (arXiv:1507.07617) in which the mass resonance case was treated. 
Chunhua Li, Hideaki Sunagawa
math.AP