S. Matsuda et Y. Ishimoto, FEIGIN-FUKS REPRESENTATIONS FOR NONEQUIVALENT ALGEBRAS OF N=4 SUPERCONFORMAL SYMMETRY, Modern physics letters A, 11(32-33), 1996, pp. 2611-2624
The N = 4 SU(2)(k) superconformal algebra has the global automorphism
of SO(4) approximate to SU(2) x SU(2) with the 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
outer automorphism group SO(4)/SU(2) = SU(2) are obtained a la Schwim
mer and Seiberg. We construct Feigin-Fuks representations with the rho
parameter embedded for the infinite set of the N = 4 nonequivalent al
gebras. In our construction the extended global SU(2) algebras labeled
by rho are self-consistently represented by fermion fields with appro
priate boundary conditions.