Scale separation on AdS$_3\times S^3$ with and without supersymmetry

Six-dimensional chiral gauged Einstein-Maxwell supergravity admits a two-parameter rotating dyonic string solution whose near horizon limit is the direct product of AdS$_3$ and a squashed three-sphere $S^3$. For a particular relation between the two parameters, the solution preserves $1/2$ supersymmetry. We determine the complete Kaluza-Klein spectrum of the theory around these AdS$_3$ backgrounds. For the supersymmetric backgrounds, the states organize into infinite towers of long and short multiplets of OSp(2|2). In a certain limit of parameters, both the supersymmetric and the non-supersymmetric spectra exhibit scale separation. In the latter case there are five topologically massive vectors and five scalars retaining finite masses with integer conformal dimensions, and in the supersymmetric case there are supersymmetric partners with half integer conformal dimensions, while all other masses diverge.