Dilatonic ghost condensate as dark energy

Federico Piazza*, Shinji Tsujikawa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

180 Citations (Scopus)


We explore a dark energy model with a ghost scalar field in the context of the runaway dilaton scenario in low-energy effective string theory. We address the problem of vacuum stability by implementing higher-order derivative terms and show that a cosmologically viable model of 'phantomized' dark energy can be constructed without violating the stability of quantum fluctuations. We also analytically derive the condition under which cosmological scaling solutions exist, starting from a general Lagrangian including the phantom type scalar field. We apply this method to the case where the dilaton is coupled to non-relativistic dark matter and find that the system tends to become quantum mechanically unstable when a constant coupling is always present. Nevertheless, it is possible to obtain a viable cosmological solution in which the energy density of the dilaton eventually approaches the present value of dark energy provided that the coupling rapidly grows during the transition to the scalar field dominated era.

Original languageEnglish
Pages (from-to)47-71
Number of pages25
JournalJournal of Cosmology and Astroparticle Physics
Issue number7
Publication statusPublished - 2004 Jul
Externally publishedYes


  • Dark energy theory
  • String theory and cosmology

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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