Characterization of ground-states for a system of $M$ coupled semilinear Schr\"odinger equations and applications

We focus on the study of ground-states for the system of $M$ coupled semilinear Schr"odinger equations with power-type nonlinearities and couplings. General results regarding existence and characterization are derived using a variational approach. We show the usefulness of such a characterization in several particular cases, including those for which uniqueness of ground-states is already known. Finally, we apply the results to find the optimal constant for the vector-valued Gagliardo-Nirenberg inequality and we study global existence, $L^2$-concentration phenomena and blowup profile for the evolution system in the $L^2$-critical power case.