Open Strings and Dualities

TL;DR

This paper reviews open-string constructions, their role in dualities, and explores non-supersymmetric models and brane configurations, highlighting how strong curvature effects blur traditional distinctions between D-branes.

Contribution

It provides a detailed review of open-string descendants, including non-supersymmetric models and brane backgrounds, emphasizing their role in dualities and non-trivial geometries.

Findings

Open-string descendants can be constructed via generalized orientation reversal.

Non-supersymmetric models exhibit novel duality properties.

Brane configurations in curved backgrounds challenge traditional D-brane distinctions.

Abstract

In the fruitful interplay between gauge fields and strings and in many conjectured M-theory dualities, open strings play a prominent role. We review the construction of open-string descendants (un-orientifolds) of closed-string theories admitting a generalized orientation reversal involution. We then specialize the construction to some classes of non-supersymmetric models in D=10 that have been recently considered in the context of duality without supersymmetry. We also discuss the propagation of open and unoriented strings on the NS pentabrane (N5-brane). This background is a prototype of the configurations of branes and orientifold planes that represent a powerful alternative to the geometric engineering of Supersymmetric Yang-Mills Theories. The resulting description of D-branes in non-trivial backgrounds looks very different from the one naively expected. In particular the very distinction between different Dp-branes becomes ambiguous in the presence of strong curvature effects.