On the Well-Posedness and Stability of Cubic and Quintic Nonlinear Schródinger Systems on T3

In this paper, we study cubic and quintic nonlinear Schrodinger systems on three-dimensional tori, with initial data in an adapted Hilbert space H-lambda(s) , and all of our results hold on rational and irrational rectangular, flat tori. In the cubic and quintic case, we prove local well-posedness for both focusing and defocusing systems. We show that local solutions of the defocusing cubic system with initial data in H-lambda(1) can be extended for all time. Additionally, we prove that global well-posedness holds in the quintic system, focusing or defocusing, for initial data with sufficiently small H-lambda(1) norm. Finally, we use the energy-Casimir method to prove the existence and uniqueness, and nonlinear stability of a class of stationary states of the defocusing cubic and quintic nonlinear Schrodinger systems.