… The first class of modified gravity theories we want to cover is … of theories goes by the name
Tensor-(Vector)-Scalar theories or … constraints that are imposed on each gravity theory. The …

… Constrained gravity approaches exploit minimal departures … We note that one can have
healthy theories with higher-than-… For clarity, we denote the Planck mass by κ in this and the …

… Interestingly, the GR limit of these modified gravity … introduction to nonmetricity theories of
modified gravity. In this very … By contrast, a healthy behavior enabling the normalization in the …

… to models of gravity and how they are constrained through … Using the HL as a paradigm of
modified gravity, we focus on its … are theories without a mass scale in addition to the Planck …

… This acts as a plausible form of modified gravity. The lightness … Instead these give rise to
healthy subluminal perturbations, and … Our primary constraints are summarized ahead in Fig. 2. …

… ∂tN − NiDiN, and explore a larger class of healthy scalar-tensor theories with three dof [25]. …
-wavelength limits. In both limits, we will see that the effect of modification of gravity comes …

… Planck mass. In the quasi-static limit, it turns out that for the effective Newton’s constant for the
… of GWs placed surprisingly stringent constraints on the theory space of gravity models, and …

… Following this path the Planck data have been recently confirmed by ATC [11], and local … to
set constraints on the theory. In the following we will choose the constants Γ0,Γ1 as to make Θ …

… on theories of dark energy (and/or modified gravity). … that constraints on the ci are indeed
driven by Planck data and … ΛCDM parameters are fixed to their Planck 2015 best-fit values here […

… constrained variational formulation of these modified Einstein equations. Then, drawing on
analogies with the Henneaux-Teitelboim action for unimodular gravity… as a healthy scalar field …