Born–Infeld inspired modifications of gravity

JB Jiménez, L Heisenberg, GJ Olmo, D Rubiera-Garcia - Physics Reports, 2018‏ - Elsevier
General Relativity has shown an outstanding observational success in the scales where it
has been directly tested. However, modifications have been intensively explored in the …

Nonmetricity formulation of general relativity and its scalar-tensor extension

L Järv, M Rünkla, M Saal, O Vilson - Physical Review D, 2018‏ - APS
Einstein's celebrated theory of gravitation can be presented in three forms: general relativity,
teleparallel gravity, and the rarely considered before symmetric teleparallel gravity …

Metric-Affine Gravity as an effective field theory

A Baldazzi, O Melichev, R Percacci - Annals of Physics, 2022‏ - Elsevier
We discuss theories of gravity with independent metric (or frame field) and connection, from
the point of view of effective field theory. We count the parity-even Lagrangian terms of …

Modified gravity: A unified approach

CG Böhmer, E Jensko - Physical Review D, 2021‏ - APS
Starting from the original Einstein action, sometimes called the Gamma squared action, we
propose a new setup to formulate modified theories of gravity. This can yield a theory with …

Probing geometric proca in metric-palatini gravity with black hole shadow and photon motion

E Ghorani, B Puliçe, F Atamurotov, J Rayimbaev… - The European Physical …, 2023‏ - Springer
Extended metric-Palatini gravity, quadratic in the antisymmetric part of the affine curvature, is
known to lead to the general relativity plus a geometric Proca field. The geometric Proca …

Scale transformations in metric-affine geometry

D Iosifidis, T Koivisto - Universe, 2019‏ - mdpi.com
This article presents an exhaustive classification of metric-affine theories according to their
scale symmetries. First it is clarified that there are three relevant definitions of a scale …

Higher-order theories of gravity: diagnosis, extraction and reformulation via non-metric extra degrees of freedom—a review

A Belenchia, M Letizia, S Liberati… - Reports on Progress in …, 2018‏ - iopscience.iop.org
Modifications of Einstein's theory of gravitation have been extensively considered in the past
years, in connection to both cosmology and quantum gravity. Higher-curvature and higher …

Radiatively stable ghost and tachyon freedom in metric affine gravity

C Marzo - Physical Review D, 2022‏ - APS
We report the existence of a ghost-and tachyon-free sector in metric affine theories of gravity,
that is invariant under diffeomorphism and a particular Abelian symmetry. In contrast with …

Metric-affine gravity and inflation

K Shimada, K Aoki, K Maeda - Physical Review D, 2019‏ - APS
We classify the metric-affine theories of gravitation, in which the metric and the connections
are treated as independent variables, by use of several constraints on the connections …

Einstein–Cartan pseudoscalaron inflation

A Di Marco, E Orazi, G Pradisi - The European Physical Journal C, 2024‏ - Springer
We study a class of early universe cosmological models based on Einstein–Cartan gravity
and including a higher derivative term corresponding to a power of the Holst scalar …