A unifying description of dark energy

By J. Gleyzes, D. Langlois, F. Vernizzi. 2014

212 citations recorded by the source corpus.

We review and extend a novel approach that we introduced recently, to describe general dark energy or scalar-tensor models. Our approach relies on an ADM formulation based on the hypersurfaces where the underlying scalar field is uniform. The advantage of this approach is that it can describe in the same language and in a minimal way a vast number of existing models, such as quintessence models, $F(R)$ theories, scalar tensor theories, their Horndeski extensions and beyond. It also naturally includes Horava-Lifshitz theories. As summarized in this review, our approach provides a unified treatment of the linear cosmological perturbations about a FLRW universe, obtained by a systematic expansion of our general action up to quadratic order. This shows that the behaviour of these linear perturbations is generically characterized by five time-dependent functions. We derive the full equations of motion in the Newtonian gauge, and obtain in particular the equation of state for dark energy perturbations, in the Horndeski case, in terms of these functions. Our unifying description thus provides the simplest and most systematic way to confront theoretical models with current and future cosmological observations.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/4b341494a78b6a6aa948ea88093f2b74d00993e6

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Citations in the corpus

Testing modified gravity at cosmological distances with LISA standard sirens (2019, methodology): “nteresting cosmological models where G4(˚) depends on time, something that can be tested with GW observations. In this set-up, is related to the eective Planck mass according to eq. (1.3) (see ref. [17]): M 2= dlnM2 e dlna ; (3.7) as follows from the discussion in section2.2.2. In this section we u”
Extended scalar-tensor theories of gravity (2016, background): “[23] pointed out that the appearance of Ṅ does not necessarily lead to an additional propagating degree of freedom since the general conformal and disformal transformation (70) can remove the Ṅ dependence.”
Effective field theory of dark energy: A review (2019, methodology): “[41, 98], but here we use the above recipe to find the mapping relations.”
Degenerate higher order scalar-tensor theories beyond Horndeski and disformal transformations (2016, background): “It would be interesting to study the cosmology of these new theories by using, for instance, the general formalism developed in [25, 26].”
Cosmology and Fundamental Physics with the Euclid Satellite (2012, background): “the review [533] for details, here mentioning only the rough principles.”
Effective description of higher-order scalar-tensor theories (2017, background): “A derivation of the quadratic action for tensor perturbations, which depends only on the parameters M2 and αT, can be found for instance in [4, 7].”
Gravitational wave decay into dark energy (2018, background): “mplies that ˛ 3. To compare with large-scale structure constraints, we can write the scale in terms of quantities constrained by observations. In particular, let us dene the dimensionless quantities [35,36] 2c+ 4m4 2 M2 Pl H 2 + 3m6 3 2M4 Pl H 2 ; B m3 3 2M2 Pl H ; H 2~m2 4 M Pl : (47) 8 The rst ”
Dark energy and modified gravity in degenerate higher-order scalar–tensor (DHOST) theories: A review (2018, background): “35) When β1 = 0, one recovers the results obtained for Horndeski and Beyond Horndeski theories (see [37]).”
Scalar-tensor theories and modified gravity in the wake of GW170817 (2017, background): “It is also worth noting that the coefficients Ξi can be related to two of the cosmological effective parameters, namely αH and β1, introduced in the effective description of dark energy in [28] and [9], extending the parameters of [29] to Beyond Horndeski and DHOST theories.”
Hamiltonian analysis of higher derivative scalar-tensor theories (2015, background): “In general, terms that depend on Ṅ or Ṅ i indicate the presence of additional degrees of freedom, but this is not always the case, as illustrated explicitly in [32] for disformal transformations and discussed in more detail in [33].”