The super D9-brane and its truncations

We consider two inequivalent truncations of the super D9-brane: the "Hetero tic" and the "Type I" truncation. Both of them lead to an N = 1 non-linear supersymmetrization of the D = 10 cosmological constant. The propagating de grees of freedom in the Heterotic and Type I truncation are given by the co mponents of a D = 10 vector multiplet and a single Majorana-Weyl spinor, re spectively. As a by-product we find that, after the Type I truncation, the Ramond-Ramond super ten-form provides an interesting reformulation of the V olkov-Akulov action. These results can be extended to all dimensions in whi ch space-time filling D-branes exist, i.e. D = 3,4, 6 and 10. (C) 1999 Publ ished by Elsevier Science B.V. All rights reserved.