 This theory has the flavor symmetry SU("N"f)L×SU("N"f)R×U(1)V This flavor symmetry SU("N"f)L×SU("N"f)R×U(1)V becomes anomalous when the background gauge field is introduced.One may use either the degrees of freedom at the far low energy limit (far “IR” ) or the degrees of freedom at the far high energy limit (far “UV”) in order to calculate the anomaly.In the former case one should only consider massless fermions or Nambu–Goldstone bosons which may be composite particles, while in the latter case one should only consider the elementary fermions of the underlying short-distance theory.