An exactly solvable model of the persistent currents in presence of   hard-core interaction in a one dimensional mesoscopic ring
  A simplest model of the persistent current in presence of many-body interaction in a mesoscopic ring is presented. The Bethe ansatz approach is used to find exact solutions. Both cases in the absence of impurity and in the presence of impurity are solved and compared. It is indicated that both impurity and hard-core interaction do not affect the result of persistent current explicitly if there is a large number of electrons in the ring. 
You-Quan Li and Zhong-Shui Ma