In this review we describe our current understanding of the properties of open string
tachyons on an unstable D-brane or brane–antibrane system in string theory. The various …

An overview of some cosmological aspects of string theory is presented. Recent
developments are emphasized, especially the attempts to derive inflation or alternatives to …

We begin by reviewing the results on the decay of unstable D-branes in type II string theory,
and the open–closed string duality proposal that arises from these studies. We then apply …

We point out that the solution of (4+ n)-dimensional gravity coupled to the dilaton and an n-
form field strength can give rise to a flat 4-dimensional universe (with a scale factor) of the …

We give a simple interpretation of the recent solutions for cosmologies with a transient
accelerating phase obtained from compactification in hyperbolic manifolds, or from S-brane …

We discuss a general iterative procedure for constructing time dependent solutions in open
string theory describing rolling of a generic tachyon field away from its maximum. These …

An sp-brane can be viewed as the creation and decay of an unstable D (p+ 1)-brane. It is
argued that the decaying half of an sp-brane can be described by a variant of boundary …

In this paper we give a review of recent attempts to understand quantum gravity on de Sitter
spaces. In particular, we discuss the holographic correspondence between de Sitter gravity …

We give a model-independent derivation of general intersecting rules for spacelike branes
(S-branes) in arbitrary dimensions d. This is achieved by directly solving bosonic field …

The description of string-theoretic s-branes at gs= 0 as exact worldsheet CFTs with a λcosh
X 0 or λe±X 0 boundary interaction is considered. Due to the imaginary-time periodicity of …