https://doi.org/10.1140/epjc/s10052-019-7333-z
Regular Article - Theoretical Physics
Screening 
in a new modified gravity model
1
Department of Physics, Istanbul Technical University, Maslak, 34469, Istanbul, Turkey
2
DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA, UK
3
Department of Physics, Boğaziçi University, Bebek, 34342, Istanbul, Turkey
4
Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apdo. Postal 48-3, 62251, Cuernavaca, Morelos, Mexico
* e-mail: akarsuo@itu.edu.tr
Received:
31
May
2019
Accepted:
21
September
2019
Published online:
14
October
2019
We study a new model of Energy-Momentum Squared Gravity (EMSG), called Energy-Momentum Log Gravity (EMLG), constructed by the addition of the term 
, envisaged as a correction, to the Einstein–Hilbert action with cosmological constant . The choice of this modification is made as a specific way of including new terms in the right-hand side of the Einstein field equations, resulting in constant effective inertial mass density and, importantly, leading to an explicit exact solution of the matter energy density in terms of redshift. We look for viable cosmologies, in particular, an extension of the standard CDM model. EMLG provides an effective dynamical dark energy passing below zero at large redshifts, accommodating a mechanism for screening in this region, in line with suggestions for alleviating some of the tensions that arise between observational data sets within the standard CDM model. We present a detailed theoretical investigation of the model and then constrain the free parameter 
, a normalisation of 
, using the latest observational data. The data does not rule out the CDM limit of our model (
), but prefers slightly negative values of the EMLG model parameter (
), which leads to the screening of . We also discuss how EMLG relaxes the persistent tension that appears in the measurements of 
within the standard CDM model.
© The Author(s), 2019
