Positive ground states for a class of superlinear (p,q)-Laplacian coupled systems involving Schr\"odinger equations

We study the existence of positive solutions for the following class of $(p,q)$-Laplacian coupled systems \[ \left\{ \begin{array}{lr} -\Delta_{p} u+a(x)|u|^{p-2}u=f(u)+ \alpha\lambda(x)|u|^{\alpha-2}u|v|^{\beta}, & x\in\mathbb{R}^{N}, -\Delta_{q} v+b(x)|v|^{q-2}v=g(v)+ \beta\lambda(x)|v|^{\beta-2}v|u|^{\alpha}, & x\in\mathbb{R}^{N}, \end{array} \right. \] where $N\geq3$ and $1\leq p\leq q<N$. Here the coefficient $\lambda(x)$ of the coupling term is related with the potentials by the condition $|\lambda(x)|\leq\delta a(x)^{\alpha/p}b(x)^{\beta/q}$ where $\delta\in(0,1)$ and $\alpha/p+\beta/q=1$. We deal with periodic and asymptotically periodic potentials. The nonlinear terms $f(s), \; g(s)$ are "superlinear" at $0$ and at $\infty$ and are assumed without the well known Ambrosetti-Rabinowitz condition at infinity. Thus, we have established the existence of positive ground states solutions for a large class of nonlinear terms and potentials. Our approach is variational and based on minimization technique over the Nehari manifold.