Power-laws f(R) theories are cosmologically unacceptable

Luca Amendola*, David Polarski, Shinji Tsujikawa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

88 Citations (Scopus)


In a recent paper,1 we have shown that f(R) = R + μR n modified gravity dark energy models are not cosmologically viable because during the matter era that precedes the accelerated stage the cosmic expansion is given by a ∼ t1/2 rather than a ∼ t 2/3, where a is a scale factor and t is the cosmic time. A recent work by Capozziello et al.2 criticized our results presenting some apparent counter-examples to our claim in f(R) = μRn models. We show here that those particular Rn models can produce an expansion as a ∼ t2/3 but this does not connect to a late-time acceleration. Hence, though acceptable f(R) dark energy models might exist, the Rn models presented in Capozziello et al. are not cosmologically viable, confirming our previous results in Ref. 1.

Original languageEnglish
Pages (from-to)1555-1561
Number of pages7
JournalInternational Journal of Modern Physics D
Issue number10
Publication statusPublished - 2007 Oct
Externally publishedYes


  • Dark energy
  • Modified gravity

ASJC Scopus subject areas

  • Mathematical Physics
  • Astronomy and Astrophysics
  • Space and Planetary Science


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