Higher-Dimensional Loop Algebras, Non-Abelian Extensions and p-Branes
  We postulate a new type of operator algebra with a non-abelian extension. This algebra generalizes the Kac--Moody algebra in string theory and the Mickelsson--Faddeev algebra in three dimensions to higher-dimensional extended objects ($p$-branes). We then construct new BRST operators, covariant derivatives and curvature tensors in the higher-dimensional generalization of loop space. 
M. Cederwall, G. Ferretti, B.E.W. Nilsson and A. Westerberg