Charged and Uncharged D-branes in various String Theories

TL;DR

This work frameworks D-brane spectra across ten-dimensional string theories through open-closed duality encoded in the modular $S$ and non-orientable $P$ matrices of boundary CFT, enabling a systematic classification of charged and uncharged branes, including non-BPS configurations. It uncovers how $P$ governs orientifold-induced spectra, tadpole constraints, and the structure of lower-dimensional branes via reduced-symmetry decompositions, while detailing tachyon couplings, gauge groups, and anomaly cancellation through Wess-Zumino terms. The paper provides a unified treatment of type 0, type I, and 0A/0B orientifolds, revealing rich spectra with both tachyonic instabilities and tachyon-free, stable configurations, and explores the implications for super-Higgs mechanisms on non-BPS branes. It also introduces fractional branes and their twisted RR charges, linking them to Green-Schwarz anomaly cancellation and to boundary states in $D_{odd}$ SU(2) WZW models, thereby connecting brane physics to deeper aspects of rational CFT and orbifold completeness.

Abstract

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 $D_{odd}$ SU(2) WZW models.