Related papers: Relaxing the Cosmological Moduli Problem
We discuss effects of cosmological moduli fields on the cosmic microwave background (CMB). If a modulus field \phi once dominates the universe, the CMB we observe today is from the decay of \phi and its anisotropy is affected by the…
Low energy effective actions arising from string theory typically contain many scalar fields, some with a very complicated potential and others with no potential at all. The evolution of these scalars is of great interest. Their late time…
We study the cosmological evolution of the volume moduli in a class of recently proposed Inflationary Universe models arising out of Type IIB string theory, where a number of the moduli fields have been stabilised through flux…
We establish the main features of homogeneous and isotropic dilaton, metric and Yang-Mills configurations in a cosmological framework. We identify a new energy exchange term between the dilaton and the Yang-Mills field which may lead to a…
Moduli fields, a natural prediction of any supergravity and superstring-inspired supersymmetry theory, may lead to a prolonged period of matter domination in the early Universe. This can be observationally viable provided the moduli decay…
We derive a constraint on the cosmic density of string moduli fields in gauge-mediated supersymmetry-breaking theories by requiring that photons emitted from the unstable moduli fields should not exceed the observed X-ray backgrounds. Since…
We investigate cosmological evolution in models where the effective potential V(\phi) may become negative for some values of the field \phi. Phase portraits of such theories in space of variables (\phi,\dot\phi,H) have several qualitatively…
We argue that the brane-world picture with matter-fields confined to 4-d domain walls and with gravitational interactions across the bulk disallows adding an arbitrary constant to the low-energy, 4-d effective theory -- which finesses the…
We estimate the abundance of the coherent oscillation of moduli, which linearly couple to matter fields through higher dimensional operators. During the (p)reheating after inflation, matter particles are efficiently produced and it can…
A complex scalar field has recently been suggested to bind galaxies and flatten the rotation curves of spirals. Its cosmological behavior is thoroughly investigated here. Such a field is shown to be a potential candidate for the…
We present a model that naturally tunes a large positive cosmological constant to a small cosmological constant. A slowly rolling scalar field decreases the cosmological constant to a small negative value, causing the universe to contract,…
We show that in generic supergravity theories the mass of the moduli during inflation is larger (or at least of the same order of magnitude) than the Hubble constant. This fact does not depends on the details of the inflation and on the…
We propose a simple but effective mechanism to realize an inflationary early universe consistent with the observed WMAP, Planck and/or BICEP2 data, which would be incorporated in various supersymmetric models of elementary particles…
We argue that more cosmological solutions in massive gravity can be obtained if the metric tensor and the tensor $\Sigma_{\mu\nu}$ defined by St\"{u}ckelberg fields take the homogeneous and isotropic form. The standard cosmology with matter…
String gas cosmology is an approach towards studying the effects of superstring theory on early universe cosmology which is based on new symmetries and new degrees of freedom of string theory. Within this context, it appears possible to…
We review some aspects of moduli in string theory. We argue that one should focus on {\it approximate moduli spaces}, and that there is evidence that such spaces exist non-perturbatively. We ask what it would mean for string theory to…
The recent measurements of the Hubble constant based on the standard $\Lambda$CDM cosmology reveal an underlying disagreement between the early-Universe estimates and the late-time measurements. Moreover, as these measurements improve, the…
We revisit the cosmological history in the presence of light moduli by including possible thermal effects in the scalar potential. The well known cosmological moduli problem regards initial energy stored in the moduli due to a misalignment…
We study moduli stabilization by thermal effects in the cosmological context. The implementation of finite temperature, which spontaneously breaks supersymmetry, induces an effective potential at one loop level. At the points where extra…
Moduli fields generically produce strong dark matter -- radiation and baryon -- radiation isocurvature perturbations through their decay if they remain light during inflation. We show that existing upper bounds on the magnitude of such…