Degeneracy and multiplicity of standing-waves of the one-dimensional non-linear Schrödinger equation for a class of algebraic non-linearities

We study the existence, the stability and the non-degeneracy of normalized standing-waves solutions to a one-dimensional non-linear Schrödinger equation. The non-linearity belongs to a class of algebraic functions appropriately defined. We can show that for some of these non-linearities one can observe the existence of degenerate minima, and the multiplicity of positive, radially symmetric minima having the same mass and the same energy. We also prove the stability of the ground-state and the stability of normalized standing-waves whose profile is a minimum of the energy constrained to the mass.