Higher Symmetries in Condensed Matter Physics
  We discuss some applications of higher symmetry groups to condensed matter systems. We give special attention to the groups SO(n) (n = 4, 5, 6, 8) in the two-dimensional Hubbard model and its generalizations, which model the high T_c cuprate superconductors. 
R. S. Markiewicz and M. T. Vaughn