This review is devoted to open strings, and in particular to the often surprising features of
their spectra. It follows and summarizes developments that took place mainly at the …

The physical motivations and the basic construction rules for type I strings and M-theory
compactifications are reviewed in the light of recent developments. The first part of this …

We consider the novel Kaluza-Klein (KK) scenario where gravity propagates in the (4+ n)-
dimensional bulk of spacetime, while gauge and matter fields are confined to the (3+ 1) …

We construct six-and four-dimensional toroidal compactifications of the type-I string with
magnetic flux on the D-branes. The open strings in this background probe a …

We show how to construct chiral tachyon-free perturbative orientifold models, where
supersymmetry is broken at the string scale on a collection of branes while, to lowest order …

We derive the effective N= 1, D= 4 supergravity for the seven main moduli of type IIA
orientifolds with D6-branes, compactified on T6/(Z2× Z2) in the presence of general fluxes …

We derive the rules to construct type IIB compact orientifolds in six and four dimensions
including D-branes and anti-D-branes. Even though the models are non-supersymmetric …

We analyze some features of the role that extra dimensions, of radius R in the TeV− 1 range,
can play in the soft breaking of supersymmetry and the spontaneous breaking of …

We show how chiral type I models whose tadpole conditions have no supersymmetric
solution can be consistently defined introducing antibranes with non-supersymmetric world …

In string theory, the brane world scenario, where the Standard Model gauge and matter
fields live inside some branes while gravitons live in the bulk, can be a viable description of …