Eur. Phys. J. C (2020) 80: 708
https://doi.org/10.1140/epjc/s10052-020-8291-1

Regular Article - Theoretical Physics

Minimally modified gravity fitting Planck data better than CDM

¹ Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, 606-8502, Japan
² Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba, 277-8583, Japan
³ APC-Astroparticule et Cosmologie Université Paris Diderot Paris 7, 75013, Paris, France
⁴ Institut Denis Poisson, Université de Tours, Université d’Orléans, Parc de Grandmont, 37200, Tours, France

^* e-mail: masroor.cp@yukawa.kyoto-u.ac.jp

Received: 8 June 2020
Accepted: 23 July 2020
Published online: 6 August 2020

Abstract

We study the phenomenology of a class of minimally modified gravity theories called theories, in which the usual general relativistic Hamiltonian constraint is replaced by a free function of it. After reviewing the construction of the theory and a consistent matter coupling, we analyze the dynamics of cosmology at the levels of both background and perturbations, and present a concrete example of the theory with a 3-parameter family of the function f. Finally, we compare this example model to Planck data as well as some later-time probes, showing that such a realization of theories fits the data significantly better than the standard CDM model, in particular by modifying gravity at intermediate redshifts, .