Improved BFT quantization of O(3) nonlinear sigma model

We newly apply the improved Batalin-Fradkin-Tyutin(BFT) Hamiltonian method to the O(3) nonlinear sigma model, and directly obtain the compact form of nontrivial first class Hamiltonian by introducing the BFT physical fields. Furthermore, following the BFV formalism, we derive the BRST invariant gauge fixed Lagrangian through the standard path-integral procedure. Finally, by introducing collective coordinates, we also study a semi-classical quantization of soliton background to conclude that the spectrum of zero modes are unchanged through the BFT procedure.