Related papers: Relaxing the Cosmological Moduli Problem
A cosmological model describing the evolution of n Ricci-flat spaces (n>1) in the presence of 1-component perfect-fluid and minimally coupled scalar field is considered. When the pressures in all spaces are proportional to the density, the…
We propose a scenario in which the cosmological domain wall and monopole problems are solved without any fine tuning of the initial conditions or parameters in the Lagrangian of an underlying filed theory. In this scenario domain walls…
The quantum field theory prediction of the cosmological constant is 120 orders of magnitude higher than the observed value. This is known as the cosmological constant problem. Here, we deal with the cosmological constant as a scalar field…
Possible existence of the primordial magnetic fields has affected the structure formation of the universe. In this paper it is shown that the initial conditions for density perturbations with magnetic fields derived in previous works are…
We discuss FLRW-cosmologies with negatively-curved spatial slices that induce a late-time freezing of all the moduli of an effective field theory through Hubble friction, independently of the moduli-space curvature. This holds for pure…
We study dynamical moduli stabilization driven by gaugino condensation in supergravity. In the presence of background radiation, there exists a region of initial conditions leading to successful stabilization. We point out that most of the…
It has been proposed that the accelerated expansion of the universe can be explained by the merging of our universe with baby universes, resulting in dark energy with a phantom-like equation of state. However, the evidence in favor of it…
We study the cosmology of K-mouflage theories at the background level. We show that the effects of the scalar field are suppressed at high matter density in the early Universe and only play a role in the late time Universe where the…
The observed dark energy in the universe might give particles inertial mass. We investigate one realization of this idea, that the dark energy field might be a decayed scalar component of a supermultiplet field in the early universe that…
We have critically compared different approaches to the cosmological constant problem, which is at the edge of elementary particle physics and cosmology. This problem is deeply connected with the difficulties formulating a theory of quantum…
We consider the cosmological implications of light travelling faster in the early Universe. We propose a prescription for deriving corrections to the cosmological evolution equations while the speed of light $c$ is changing. We then show…
We consider a cosmologically consistent scenario with a heavy Polonyi field. The Polonyi field with a mass of ${\cal O}(100){\rm\,TeV}$ decays before the Big-Bang Nucleosynthesis (BBN) and avoids the severe constraint from the BBN. However,…
We consider ultralight scalar dark matter that couples to right-handed neutrinos. Due to the high density of neutrinos in the early universe, the background neutrino density dominates the dynamics of the scalar field, and qualitatively…
In the context of Effective Field Theory, the Hilbert space of states increases in an expanding universe. Hence, the time evolution cannot be unitary. The formation of structure is usually studied using effective field theory techniques. We…
The cosmological constant problem represents a profound conflict between quantum field theory and general relativity. Unimodular gravity offers a compelling starting point by de-gravitating the vacuum energy of the Standard Model, but this…
The abundance of clusters is a classical cosmological probe sensitive to both the geometrical aspects and the growth rate of structures. The abundance of clusters of galaxies measured by Planck has been found to be in tension with the…
A toy landscape sector is introduced as a compactification of the Einstein-Maxwell model on a product of two-spheres. Features of the model include: moduli stabilization, a distribution of the effective cosmological constant of the…
The cosmological constant problem is one of the greatest challenges in contemporary physics, since it is deeply rooted in the problematic interplay between quantum fields and gravity. The aim of this work is to review the key conceptual…
Hoyle and Narlikar's $C$-field cosmology is extended in the framework of higher dimensional spacetime and a class of exact solutions is obtained. Adjusting the arbitrary constants of integration one can show that our model is amenable to…
Cosmological stasis is a new type of epoch in the cosmological timeline during which the cosmological abundances of different energy components -- such as vacuum energy, matter, and radiation -- remain constant despite the expansion of the…