A Covariant Action for the Eleven Dimensional Superstring

We suggest a super Poincar\'e invariant action for closed eleven dimensional superstring. The sector of physical variables $x^i$, $\theta_a$, $\bar\theta_{\dot a}$, with $a,\dot a=1...8$ and $x^i$ the transverse part of the D=11 $x^\mu$ coordinate is shown to possess free dynamics.Comment: 15 pages, LaTex file, to appear in Mod. Phys. Lett. A (1997

Supplementation of reducible constraints and the Green-Schwarz superstring

We apply the supplementation trick [26] to the Green-Schwarz superstring. For type IIB theory both first and second class constraints are covariantly separated and then arranged into irreducible sets in the initial formulation. For N=1 Green-Schwarz superstring we propose a modified action which is equivalent to the initial one. Fermionic first and second class constraints are covariantly separated, the first class constraints turn out to be irreducible. We discuss also equations of motion in the covariant gauge for $\kappa$-symmetry. For type IIA theory the same modification leads to formulation with irreducible second class constraints.Comment: 14 pages, LaTex twice, Minor correction