Cosmological gravitational particle production (CGPP) is the creation of particles in an
expanding universe due solely to their gravitational interaction. These particles can play an …

We review recent progress in the construction of modified gravity models as alternatives to
dark energy as well as the development of cosmological tests of gravity. Einstein's theory of …

Despite its continued observational successes, there is a persistent (and growing) interest in
extending cosmology beyond the standard model, Λ CDM. This is motivated by a range of …

A century ago, Einstein formulated his elegant and elaborate theory of General Relativity,
which has so far withstood a multitude of empirical tests with remarkable success …

A bstract The phenomenon of cosmological gravitational particle production (CGPP) is
expected to occur during the period of inflation and the transition into a hot big bang …

This review is dedicated to recent progress in the field of classical, interacting, massive spin-
2 theories, with a focus on ghost-free bimetric theory. We will outline its history and its …

Explaining the origin of the acceleration of the expansion of the Universe remains as
challenging as ever. In this review, we present different approaches from dark energy to …

Bimetric theory describes gravitational interactions in the presence of an extra spin-2 field.
Previous work has suggested that its cosmological solutions are generically plagued by …

Bimetric gravity is a theory of gravity that posits the existence of two interacting and
dynamical metric tensors. The spectrum of bimetric gravity consists of a massless and a …

Following the path of minimalism in alternative theories of gravity, we construct the" Minimal
Theory of Bigravity"(MTBG), a theory of two interacting spin-2 fields that propagates only four …