SU(3)/SU(2): the simplest Wess-Zumino-Witten term

The observation that SU(3)/SU(2) ~ S^5 implies the existence of a particularly simple quantized topological action, or Wess-Zumino-Witten (WZW) term. This action plays an important role in anomaly cancellation in extensions of the Standard Model electroweak sector. A closed form is presented for the action coupled to arbitrary gauge fields. The action is shown to be equivalent to a limit of the WZW term for SU(3) x SU(3) / SU(3). By reduction of SU(3) x U(1) / SU(2) x U(1) to SU(2) x U(1) / U(1), the construction gives a topological derivation of the WZW term for the Standard Model Higgs field.