Feigin-Fuchs Representations for Nonequivalent Algebras of N=4   Superconformal Symmetery
  The $N=4$ SU(2)$_k$ superconformal algebra has the global automorphism of SO(4) $\approx$ SU(2)$\times$SU(2) with the {\it left} factor as the Kac-Moody gauge symmetry. As a consequence, an infinite set of independent algebras labeled by $\rho$ corresponding to the conjugate classes of the {\it outer} automorphism group SO(4)/SU(2)=SU(2) are obtained \`a la Schwimmer and Seiberg. We construct Feigin-Fuchs representations with the $\rho$ parameter embedded for the infinite set of the $N=4$ nonequivalent algebras. In our construction the extended global SU(2) algebras labeled by $\rho$ are self-consistently represented by fermion fields with appropriate boundary conditions. 
Satoshi Matsuda and Yukitaka Ishimoto