A master screening equation is derived for luminal Horndeski gravity that recovers Vainshtein and Chameleon mechanisms and introduces Phaedrus screening with screening radius scaling linearly with source mass.
K-mouflage Cosmology: the Background Evolution
3 Pith papers cite this work, alongside 72 external citations. Polarity classification is still indexing.
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abstract
We study the cosmology of K-mouflage theories at the background level. We show that the effects of the scalar field are suppressed at high matter density in the early Universe and only play a role in the late time Universe where the deviations of the Hubble rate from its $\Lambda$-CDM counterpart can be of the order five percent for redshifts $1 \lesssim z \lesssim 5$. Similarly, we find that the equation of state can cross the phantom divide in the recent past and even diverge when the effective scalar energy density goes negative and subdominant compared to matter, preserving the positivity of the squared Hubble rate. These features are present in models for which Big Bang Nucleosynthesis is not affected. We analyze the fate of K-mouflage when the nonlinear kinetic terms give rise to ghosts, particle excitations with negative energy. In this case, we find that the K-mouflage theories can only be considered as an effective description of the Universe at low energy below $1$ keV. In the safe ghost-free models, we find that the equation of state always diverges in the past and changes significantly by a few percent since $z\lesssim 1$.
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background 1representative citing papers
Cosmological data can constrain only a handful of EFT parameters for single-scalar dark energy; extended models show modest preference over Λ but remain underdetermined and challenged by fifth forces and screening.
Einstein-Gauss-Bonnet inflation can yield positive spectral-index running with a viable era under ACT-like hints, while scalar-field and F(R) models largely cannot.
citing papers explorer
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A Master Equation for Screening in Luminal Horndeski Gravity
A master screening equation is derived for luminal Horndeski gravity that recovers Vainshtein and Chameleon mechanisms and introduces Phaedrus screening with screening radius scaling linearly with source mass.
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The Status of Single Scalar Field Dark Energy
Cosmological data can constrain only a handful of EFT parameters for single-scalar dark energy; extended models show modest preference over Λ but remain underdetermined and challenged by fifth forces and screening.
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ACT Data and Positive Running of the Spectral Index for Scalar Theory and Modified Gravity
Einstein-Gauss-Bonnet inflation can yield positive spectral-index running with a viable era under ACT-like hints, while scalar-field and F(R) models largely cannot.