Persistent currents in a two-component Bose-Einstein condensate confined in a ring potential

We present variational and numerical solutions for the problem of stability of persistent currents in a two-component Bose-Einstein condensate of distinguishable atoms which rotate in a ring potential. We consider the general class of solutions of constant density in the two components separately, thus providing an alternative approach of the solution of the same problem given recently by Zhigang Wu and Eugene Zaremba [Phys. Rev. A {\bf 88}, 063640 (2013)]. Our approach provides a physically transparent solution of this delicate problem. Finally, we give a unified and simple picture of the lowest-energy state of the system for large values of the coupling.