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 …

The Swampland program aims to distinguish effective theories which can be completed into
quantum gravity in the ultraviolet from those which cannot. This article forms an introduction …

This white paper summarizes recent progress in the cosmological bootstrap, an approach to
the study of the statistics of primordial fluctuations from consistency with unitarity, locality and …

We study constraints imposed by two proposed string Swampland criteria on cosmology.
These criteria involve an upper bound on the range traversed by scalar fields as well as a …

Primordial black holes formed in the early Universe via gravitational collapse of over-dense
regions may contribute a significant amount to the present dark matter relic density. Inflation …

Several pulsar timing arrays including NANOGrav, EPTA, PPTA, and CPTA have recently
reported the observation of a stochastic background of gravitational wave spectrum in the …

The recently introduced swampland criterion for de Sitter [17] can be viewed as a
(hierarchically large) bound on the smallness of the slow roll parameter 𝜖 V. This leads us to …

Axions comprise a broad class of particles that can play a major role in explaining the
unknown aspects of cosmology. They are also well-motivated within high energy physics …

The axion is a light pseudoscalar particle postulated to solve issues with the Standard
Model, including the strong CP problem and the origin of dark matter. In recent years, there …

A bstract In the Emergence Proposal in Quantum Gravity it is conjectured that all light-
particle kinetic terms are absent in the fundamental ultraviolet theory and are generated by …