Charged and uncharged D-branes in various string theories Original Research Article

We describe how the D-brane spectra of the various ten-dimensional string theories can be related to general properties of the open–closed duality, encoded in the S and P matrices of the conformal field theory. We also complete the classification and the description of non-BPS branes in these string theories, elucidating their non-Abelian structures and the nature of the corresponding super-Higgs mechanisms. We find that the type 0 theories and their orientifolds have two types of uncharged branes, distinguished by their couplings to the closed string tachyon. We also find that the 0A orientifold has the unusual feature of having charged and uncharged branes with identical world-volume dimensions. We conclude with some comments on fractional branes, elucidating their role in connection with the boundary states of Dodd SU(2) WZW models.