“…If (Φ ω 1 , Ψ ω 2 ) is not only a critical point, but in fact a global minimizer of the constrained variational problem for H(u, v), then (1.8) is called a ground-state solution of (1.2). In some cases, namely when p = r = 2q = 4 and under certain conditions on α, β, and τ, it is possible to show further that the ground-state solutions are solitary waves with the usual sech-profile (see, for example, [33,31]). …”