CMB constraints on DHOST theories
Abstract
We put constraints on the degenerate higher-order scalar-tensor (DHOST) theories using the Planck 2018 likelihoods. In our previous paper, we developed a Boltzmann solver incorporating the effective field theory parameterised by the six time-dependent functions, αi (i = B, K, T, M, H) and β 1, which can describe the DHOST theories. Using the Markov-Chain Monte-Carlo method with our Boltzmann solver, we find the viable parameter region of the model parameters characterising the DHOST theories and the other standard cosmological parameters. First, we consider a simple model with α = ΩDE(t)/ΩDE(t 0), α B = α T = α M = α H = 0 and β 1 = β 1,0ΩDE(t)/ΩDE(t 0) in the ΛCDM background where t 0 is the present time and obtain β 1,0 = 0.032-0.016 +0.013 (68% c.l.). Next, we focus on another theory given by ℒDHOST = X + c 3 X□ϕ/Λ3 + (M pl 2/2 + c 4 x 2/Λ6)R + 48c 4 2 X 2/ (M pl 2Λ12 + 2c 4Λ6 X 2)ϕμ ϕμρ ϕρν ϕν with X := ∂μϕ∂μϕ and two positive constant parameters, c 3 and c 4. In this model, we consistently treat the background and the perturbations, and obtain c 3 = 1.59+0.26 -0.28 and the upper bound on c 4, c 4 < 0.0088 (68% c.l.).
- Publication:
-
Journal of Cosmology and Astroparticle Physics
- Pub Date:
- October 2022
- DOI:
- 10.1088/1475-7516/2022/10/035
- arXiv:
- arXiv:2205.11559
- Bibcode:
- 2022JCAP...10..035H
- Keywords:
-
- cosmological parameters from CMBR;
- modified gravity;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- General Relativity and Quantum Cosmology
- E-Print:
- 10 pages, 4 figures, 1 table