• Corpus ID: 119361607

Mirage resolution of cosmological singularities

  title={Mirage resolution of cosmological singularities},
  author={Fr{\'e}d{\'e}ric Leblond},
  journal={arXiv: High Energy Physics - Theory},
  • F. Leblond
  • Published 22 March 2004
  • Physics
  • arXiv: High Energy Physics - Theory
We study time-dependent backgrounds in the low energy regimes of string theories. In particular the emphasis is on the general study of exotic phenomena such as positive acceleration and gravitational bounces. We generalize the usual Hawking-Penrose cosmological singularity theorems to higher-dimensional spacetimes and discuss their implications for time-dependent solutions in supergravity theories. The explicit examples we consider fall in two categories. First we consider effective lower… 
Localized Intersections of Non-Extremal p-branes and S-branes
A class of solutions to Supergravity in 10 or 11 dimensions is presented which extends the non-standard or semi-local intersections of Dp-branes to the case of non-extremal p-branes. The type of
Answering a basic objection to bang/crunch holography
The current cosmic acceleration does not imply that our Universe is basically de Sitter-like: in the first part of this work we argue that, by introducing matter into anti-de Sitter spacetime in a
A family of generalized S-brane solutions with orthogonal intersection rules and n Ricci-flat factor spaces in the theory with several scalar fields, antisymmetric forms and multiple scalar potential


A Note on the singularity theorem for supergravity SD-branes
Recently the cosmological singularity theorems were shown to exclude non-singular full SD-brane gravitational backgrounds. We comment on the relation between this and previous work as well as provide
Comments on Cosmological Singularities in String Theory
We compute string scattering amplitudes in an orbifold of Minkowski space by a boost, and show how certain divergences in the four point function are associated with graviton exchange near the
Rolling Tachyon
We discuss construction of classical time dependent solutions in open string (field) theory, describing the motion of the tachyon on unstable D-branes. Despite the fact that the string field theory
String Propagation in the Presence of Cosmological Singularities
We study string propagation in a spacetime with positive cosmological constant, which includes a circle whose radius approaches a finite value as |t|??, and goes to zero at t = 0. Near this
Comments on supergravity description of S-branes
This is a note on the coupled supergravity-tachyon matter system, which has been earlier proposed as a candidate for the effective space-time description of S-branes. In particular, we study an
On Bouncing Brane-Worlds, S-branes and Branonium Cosmology
We present several higher-dimensional spacetimes for which observers living on 3-branes experience an induced metric which bounces. The classes of examples include boundary branes on generalized
Does the Tachyon Matter
Abstract We study time-dependent solutions of Einstein–Maxwell gravity in four dimensions coupled to tachyon matter—the Dirac–Born–Infeld Lagrangian that provides an effective description of a
Strings in Time-Dependent Orbifolds
We continue and extend our earlier investigation ``Strings in a Time-Dependent Orbifold'' (hep-th/0204168). We formulate conditions for an orbifold to be amenable to perturbative string analysis and
Accelerating cosmologies from exponential potentials
An exponential potential of the form V ~ exp(−2c/Mp) arising from the hyperbolic or flux compactification of higher-dimensional theories is of interest for getting short periods of accelerated