Graceful exit and energy conditions in string cosmology

Ram Brustein, Richard Madden

Research output: Contribution to journalArticlepeer-review

85 Scopus citations


String cosmology solutions are examined in a generalized phase-space including sources representing arbitrary corrections to lowest order string-dilaton-gravity effective action. We find a set of necessary conditions for a graceful exit transition from a dilaton-driven inflationary phase to a radiation dominated era. We show that sources allowing such a transition have to violate energy conditions similar to those appearing in singularity theorems of general relativity. Since familiar classical sources, excepting spatial curvature, obey these energy conditions we conclude that a generic graceful exit in string cosmology requires a new effective phase of matter. Our results clarify and generalize previous analyses and enable us to critically reexamine proposed non-singular cosmologies.

Original languageEnglish
Pages (from-to)110-118
Number of pages9
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number2-4
StatePublished - 2 Oct 1997

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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