A number of challenges to the standard Λ CDM model have been emerging during the past
few years as the accuracy of cosmological observations improves. In this review we discuss …

The exploration of the universe has recently entered a new era thanks to the multi-
messenger paradigm, characterized by a continuous increase in the quantity and quality of …

Horizon-scale images of black holes (BHs) and their shadows have opened an
unprecedented window onto tests of gravity and fundamental physics in the strong-field …

We review applications of string theory to cosmology, from primordial times to the present-
day accelerated expansion. Starting with a brief overview of cosmology and string …

In this review we present a thoroughly comprehensive survey of recent work on modified
theories of gravity and their cosmological consequences. Amongst other things, we cover …

We propose a new higher-dimensional mechanism for solving the hierarchy problem. The
weak scale is generated from the Planck scale through an exponential hierarchy. However …

Conventional wisdom states that Newton's force law implies only four noncompact
dimensions. We demonstrate that this is not necessarily true in the presence of a …

In this paper the current release of the Monte Carlo event generator Sherpa, version 1.1, is
presented. Sherpa is a general-purpose tool for the simulation of particle collisions at high …

We review in detail a number of approaches that have been adopted to try and explain the
remarkable observation of our accelerating universe. In particular we discuss the arguments …

The status of experimental tests of general relativity and of theoretical frameworks for
analyzing them is reviewed and updated. Einstein's equivalence principle (EEP) is well …