The Grassmannian sigma model in SU(2) Yang–Mills theory

Spin–charge separation in pure SU(2) Yang–Mills theory was recently found to involve the dynamics of an O(3) nonlinear sigma model and, seemingly, a Grassmannian nonlinear sigma model. In this paper we explicitly construct the Grassmannian sigma model of the form appearing in the spin–charge separated SU(2) theory through a quaternionic decomposition of the manifold, thus verifying its relevance in this context. The coupling between this model and the O(3) nonlinear sigma model is further commented upon.