The 1/r2 t-J model in a magnetic field
  We study the one-dimensional supersymmetric t-J model with 1/r2 interaction threaded by magnetic flux. Because of the long range interaction, the effect of this flux leads to a modification of the electron hopping term. We present an exact solution of this model for all values of the flux, concisely formulated as a set of Bethe-ansatz-like equations. This allows a computation of the persistent currents at zero temperature. It is found that the system violates Leggett's conjecture despite the fact that the long range t-J model is a special example of the Luttinger liquid university class. 
J. T. Liu and D. F. Wang