The quantization of the chiral Schwinger model based on the BFT-BFV   formalism II
  We apply an improved version of Batalin-Fradkin-Tyutin (BFT) Hamiltonian method to the a=1 chiral Schwinger Model, which is much more nontrivial than the a>1.$ one. Furthermore, through the path integral quantization, we newly resolve the problem of the non-trivial $\delta$ function as well as that of the unwanted Fourier parameter $\xi$ in the measure. As a result, we explicitly obtain the fully gauge invariant partition function, which includes a new type of Wess-Zumino (WZ) term irrelevant to the gauge symmetry as well as usual WZ action. 
Mu-In Park, Young-Jai Park, and Sean J. Yoon