N=2 AFFINE SUPERALGEBRAS AND HAMILTONIAN REDUCTION IN N=2 SUPERSPACE

We construct N=2 affine current algebras for the superalgebras sl(n/n - 1)((1)) in terms of N=2 supercurrents subjected to nonlinear constra ints and discuss the general procedure of the hamiltonian reduction in N=2 superspace at the classical level. We consider in detail the simp lest case of N=2 sl(2/1)((1)) and show how N=2 superconformal algebra in N=2 superspace follows via the hamiltonian reduction. Applying the hamiltonian reduction to the case of N=2 sl(3/2)((1)) we find two new extended N=2 superconformal algebras in a manifestly supersymmetric N= 2 superfield form. Decoupling of four component currents of dimension 1/2 in them yields, respectively, u(2/1) and u(3) Knizhnik-Bershadsky superconformal algebras. We also discuss how the N=2 superfield formul ations of N=2 W-3 and N=2 W-3((2)) superconformal algebras come out in this framewo rk, as well as some unusual extended N=2 superconformal algebras containing constrained N=2 stress tensor and/or spin 0 superc urrents.