N=4 Superconformal Symmetry for the Covariant Quantum Superstring

We extend our formulation of the covariant quantum superstring as a WZNW model with N=2 superconformal symmetry to N=4. The two anticommuting BRST charges in the N=4 multiplet of charges are the usual BRST charge Q_S and a charge Q_V proposed by Dijkgraaf, Verlinde and Verlinde for topological models. Using our recent work on "gauging cosets", we then construct a further charge Q_C which anticommutes with Q_S + Q_V and which is intended for the definition of the physical spectrum.Comment: LaTeX, 18 pages, no figure

The Covariant Quantum Superstring and Superparticle from their Classical Actions

We develop an approach based on the Noether method to construct nilpotent BRST charges and BRST-invariant actions. We apply this approach first to the holomorphic part of the flat-space covariant superstring, and we find that the ghosts b, c_z which we introduced by hand in our earlier work, are needed to fix gauge symmetries of the ghost action. Then we apply this technique to the superparticle and determine its cohomology. Finally, we extend our results to the combined left- and right-moving sectors of the superstring.Comment: 14 pages, harmva

Type I background fields in terms of type IIB ones

We choose such boundary conditions for open IIB superstring theory which preserve N=1 SUSY. The explicite solution of the boundary conditions yields effective theory which is symmetric under world-sheet parity transformation $\Omega:\sigma\to-\sigma$. We recognize effective theory as closed type I superstring theory. Its background fields,beside known $\Omega$ even fields of the initial IIB theory, contain improvements quadratic in $\Omega$ odd ones.Comment: 4 revtex pages, no figure