Positivity bounds on dark energy: when matter matters

Claudia de Rham, Scott Melville, Johannes Noller

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Positivity bounds - constraints on any low-energy effective field theory imposed by the fundamental axioms of unitarity, causality and locality in the UV - have recently been used to constrain scalar-tensor theories of dark energy. However, the coupling to matter fields has so far played a limited role. We show that demanding positivity when including interactions with standard matter fields leads to further constraints on the dark energy parameter space. We demonstrate how implementing these bounds as theoretical priors affects cosmological parameter constraints and explicitly illustrate the impact on a specific Effective Field Theory for dark energy. We also show in this model that the existence of a standard UV completion requires that gravitational waves must travel superluminally on cosmological backgrounds.
Original languageEnglish
Article number018
Number of pages26
JournalJournal of Cosmology and Astroparticle Physics
Issue number08
Publication statusPublished - 10 Aug 2021


  • cosmological parameters from CMBR
  • dark energy theory
  • modified gravity
  • UKRI
  • STFC
  • ST/S004572/1
  • EP/T017481/1
  • s ST/P000681/1
  • ST/T000694/1
  • ST/P000762/1
  • ST/T000791/1
  • TC_highlight


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