On two superintegrable nonlinear oscillators in N dimensions

We consider the classical superintegrable Hamiltonian system given by Hλ = T + U = p 2 2(1 + λq2) ω2q2 2(1 + λq2) where U is known to be the “intrinsic ” oscillator potential on the Darboux spaces of nonconstant curvature determined by the kinetic energy term T and parametrized by λ. We show that Hλ is Stäckel equivalent to the free Euclidean motion, a fact that directly provides a curved Fradkin tensor of constants of motion for Hλ. Furthermore, we analyze in terms of λ the three different underlying manifolds whose geodesic motion is provided by T. As a consequence, we find that Hλ comprises three different nonlinear physical models that, by constructing their radial effective potentials, are shown to be two different nonlinear oscillators and an infinite barrier potential. The quantization of these two oscillators and its connection with spherical confinement models is briefly discussed. PACS: 02.30.Ik 05.45.-a 45.20.J