Nonlinear Grassmann Sigma Models in Any Dimension and An Infinite Number   of Conserved Currents
  We first consider nonlinear Grassmann sigma models in any dimension and next construct their submodels. For these models we construct an infinite number of nontrivial conserved currents. Our result is independent of time-space dimensions and, therfore, is a full generalization of that of authors (Alvarez, Ferreira and Guillen). Our result also suggests that our method may be applied to other nonlinear sigma models such as chiral models, $G/H$ sigma models in any dimension. 
Kazuyuki Fujii, Yasushi Homma and Tatsuo Suzuki