A holographic model of quantum Hall transition

We consider a phenomenological holographic model, inspired by the D3/D7 system with a (2+1)(2+1)-dimensional intersection, at finite chemical potential and magnetic field. At large 't Hooft coupling the system is unstable and needs regularization; the UV cutoff can be decoupled by considering a certain double scaling limit. At finite chemical potential the model exhibits a phase transition between states with filling fractions plus and minus one-half as the magnetic field is varied. By varying the parameters of the model, this phase transition can be made to happen at arbitrary values of the magnetic field.