The $N=2$ supersymmetric unconstrained matrix GNLS hierarchies

Abstract

The generalization of the $N=2$ supersymmetric chiral matrix $(k|n,m)$--GNLS hierarchy to the case when matrix entries are bosonic and fermionic unconstrained $N=2$ superfields is proposed. This is done by exhibiting the corresponding matrix Lax--pair representation in terms of $N=2$ unconstrained superfields. It is demonstrated that when matrix entries are chiral and antichiral $N=2$ superfields, it reproduces the $N=2$ chiral matrix $(k|n,m)$-GNLS hierarchy, while in the scalar case, $k=1$, it is equivalent to the $N=2$ supersymmetric multicomponent hierarchy. The simplest example --- the $N=2$ unconstrained $(1|1,0)$--GNLS hierarchy --- and its reduction to the $N=2$ supersymmetric ${\alpha}=1$ KdV hierarchy are discussed in more detail, and its rich symmetry structure is uncovered.