The production of a stochastic background of gravitational waves is a fundamental
prediction of any cosmological inflationary model. The features of such a signal encode …

We consider a higher-derivative generalization of disformal transformations in D-
dimensional spacetime and clarify the conditions under which they form a group with respect …

A bstract The R 2 inflation which is an extension of general relativity (GR) by quadratic scalar
curvature introduces a quasi-de Sitter expansion of the early Universe governed by Ricci …

We investigate the propagation of gravitational waves on a black hole background within the
low-energy effective field theory of gravity, where effects from heavy fields are captured by …

Modified expansion rates in the early Universe prior to big bang nucleosynthesis are
common in modified gravity theories, and can have a significant impact on the generation of …

In “modified” gravity the observed acceleration of the universe is explained by changing the
gravitational force law or the number of degrees of freedom in the gravitational sector. Both …

The impact of the existence of gravitons with non-vanishing masses on the B-modes of the
Cosmic Microwave Background (CMB) is investigated. We also focus on putative …

Most, if not all, scalar-tensor theories are equivalent to General Relativity with a disformally
coupled matter sector. In extra-dimensional theories such a coupling can be understood as …

A disformal transformation is a very useful tool to analyze a general effective theory
description of inflation. It can for example be used to set the tensor sound speed to unity …

General relativity and the cosmological concordance model (? CDM) successfully explain a
myriad of observations. The perihelion precession of Mercury; the polarization of the cosmic …