IIB-Branes and New Spacetime Superalgebras

We provide a classification of the IIB D$p$- and NS$p$-branes in which the brane action exists due to a non-trivial class of the Chevalley-Eilenberg cohomology of free differential algebras. We then present a new geometric formulation of the IIB D$p$- and NS$p$-branes ($p\leq 5$) in which the manifestly superinvariant Wess-Zumino terms are constructed in terms of the supersymmetric currents. The supercurrents are obtained by using supergroup manifolds corresponding to the IIB-brane superalgebra, which is characterized by the generators of D3-, D5-, NS5- and KK5-branes in addition to the previously introduced generators of supertranslations, F- and D-strings. The charges of D1-, F1- and D3-branes are related to those of the M-algebra, but some charges of D5- and NS5-branes are not. The S-duality of the type-IIB theory is realized as transformations of the supercurrents generalizing the SO(2) R-symmetry of the superalgebra. We thus find that the superalgebra is lifted into twelve-dimensions with signature (11,1).