Axial anomalies in gauge theory by exact renormalization group method ∗

The global chiral symmetry of a SU(2) gauge theory is studied in the framework of renormalization group (RG). The theory is defined by the RG flow equations in the infrared cutoff Λ and the boundary conditions for the relevant couplings. The physical theory is obtained at Λ = 0. In our approach the symmetry is implemented by choosing the boundary conditions for the relevant couplings not at the ultraviolet point Λ = Λ 0 → ∞ but at the physical value Λ = 0. As an illustration, we compute the triangle axial anomalies.