Inflationary solutions in the brane world and their geometrical interpretation

Justin Khoury, Paul J. Steinhardt

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


We consider the cosmology of a pair of domain walls bounding a five-dimensional bulk space-time with a negative cosmological constant, in which the distance between the branes is not fixed in time. Although there are strong arguments to suggest that this distance should be stabilized in the present epoch, no such constraints exist for the early universe and thus non-static solutions might provide relevant inflationary scenarios. We find the general solution for the standard ansatz where the bulk is foliated by planar-symmetric hypersurfaces. We show that in all cases the bulk geometry is that of anti–de Sitter (Formula presented) space. We then present a geometrical interpretation for the solutions as embeddings of two de Sitter (Formula presented) surfaces in (Formula presented) which provide a simple interpretation of the physical properties of the solutions. A notable feature explained in the analysis is that two-way communication between branes expanding away from one another is possible for a finite amount of time, after which communication can proceed in one direction only. The geometrical picture also shows that our class of solutions (and related solutions in the literature) is not completely general, contrary to some claims. We then derive the most general solution for two walls in (Formula presented) This includes novel cosmologies where the brane tensions are not constrained to have opposite signs. The construction naturally generalizes to arbitrary FRW cosmologies on the branes.

Original languageEnglish (US)
Pages (from-to)13
Number of pages1
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number10
StatePublished - 2001

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


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