We give a survey of the present status of the microstate geometries called superstrata.
Superstrata are smooth, horizonless solutions of six-dimensional supergravity that represent …

We consider scale invariant theories which couple gravity to Maxwell fields and
antisymmetric tensor fields with a dilaton field. We exhibit in a unified way solutions …

Nature's simplest field, the scalar field, has been the protagonist of physical theories for a
long time. Even before the publication of the theory of general relativity G. Nordström …

A weakly coupled scalar field Φ with a simple exponential potential V= MP 4 exp (− λ Φ/MP)
where MP is the reduced Planck mass, and λ> 2, has an attractor solution in a radiation or …

A homogeneous isotropic cosmological model driven by a scalar field with an exponential
potential is studied. It is shown that there is a solution with power-law inflation, and this …

This article critically reviews the proposal for addressing the cosmological constant problem
within the framework of supersymmetric large extra dimensions (SLED), as recently …

These lectures on the cosmological constant problem were prepared for the X Mexican
School on Gravitation and Mathematical Physics. The problem itself is explained in detail …

We study quintessence cosmologies in the context of scalar-tensor theories of gravity, where
a scalar field φ, assumed to provide most of the cosmic energy density today, is …

In this paper we consider cosmological models containing a self-interacting scalar field
possessing a potential of the form V (φ)= Λ exp (− λφ). We investigate the inflationary nature …

These notes present a brief introduction tonaturalness' problems in cosmology, and to the
Cosmological Constant Problem in particular. The main focus is theold'cosmological …