Related papers: Non-critical String Cosmologies
Non-commutative inflation is a modification of standard general relativity inflation which takes into account some effects of the space-time uncertainty principle motivated by ideas from string theory. The corrections to the primordial…
We investigate how the use of higher wavenumbers (smaller scales) in the galaxy clustering power spectrum influences cosmological constraints. We take into account uncertainties from nonlinear density fluctuations, (scale dependent) galaxy…
Critical points represent a subset of special points tracing cosmological structures, carrying remarkable topological properties. They thus offer a richer high-level description of the multiscale cosmic web, being more robust to systematic…
Cosmological implication of rolling tachyons is reported in the context of effective field theory. With a brief review of rolling tachyons in both flat and curved spacetimes, we study the string cosmological model with both tachyon and…
Non-singular two and three dimensional string cosmologies are constructed using the exact conformal field theories corresponding to SO(2,1)/SO(1,1) and SO(2,2)/SO(2,1). All semi-classical curvature singularities are canceled in the exact…
The collapse barrier, $\delta_{c}$, of the field clusters located in the low-density environment is deterministic rather than diffusive, unlike that of the wall counterparts located in the superclusters. Analyzing the data from the…
We have investigated the cosmological scenarios with a four dimensional effective action which is connected with multidimensional, supergravity and string theories. The solution for the scale factor is such that initially universe undergoes…
This is a set of lectures on the gauge/string duality and non-critical strings, with a particular emphasis on the discretized, or matrix model, approach. After a general discussion of various points of view, I describe the recent…
It is shown that if a small negative cosmological constant is added to quintessence models with equation of state $p=\omega\rho$ on the range $-1 <\omega < -1/3$, the resulting scenarios could not contain any future event horizons.…
We consider the theory obtained by adding to the usual string frame dilaton gravity action specially constructed higher derivative terms motivated by the limited curvature construction of [MukhanovET1992a] and determine the spatially…
A quintessence scalar field or cosmon interacting with neutrinos can have important effects on cosmological structure formation. Within growing neutrino models the coupling becomes effective only in recent times, when neutrinos become…
`Old' String Theory is a theory of one-dimensional extended objects, whose vibrations correspond to excitations of various target-space field modes including gravity. In these lectures I will give an introduction to low-energy Effective…
We present non-critical Bianchi type $I$ string cosmology solutions in the presence of central charge deficit term $\Lambda$. The leading order string frame curvature appears to be in the high curvature limit $R\alpha'\gtrsim1$, which…
We use a wide range of observations to constrain cosmological models possessing a significant asymmetry in the lepton sector, which offer perhaps the best chance of reconciling a critical-density Universe with current observations. The…
Focusing on both small separations and Baryonic Acoustic Oscillation scales, the cosmic evolution of the clustering properties of peak, void, wall, and filament-type critical points is measured using two-point correlation functions in…
Recently it has been shown that string gas cosmology, an alternative model of the very early universe which does not involve a period of cosmological inflation, can give rise to an almost scale invariant spectrum of metric perturbations.…
The detection of primordial non-Gaussianity could provide a powerful means to test various inflationary scenarios. Although scale-invariant non-Gaussianity (often described by the $f_{NL}$ formalism) is currently best constrained by the…
We perform a detailed dynamical analysis of various cosmological scenarios in extended (varying-mass) nonlinear massive gravity. Due to the enhanced freedom in choosing the involved free functions, this cosmological paradigm allows for a…
We show that growing neutrino models, in which the growing neutrino mass stops the dynamical evolution of a dark energy scalar field, lead to a substantial neutrino clustering on the scales of superclusters. Nonlinear neutrino lumps form at…
String cosmology solutions are examined in a generalized phase-space including sources representing arbitrary corrections to lowest order string-dilaton-gravity effective action. We find a set of necessary conditions for a graceful exit…