Related papers: Non-singular string cosmology via $\alpha^{\prime}…
This note deals with the possibility of non-trivial cosmological solutions given by quantum corrections in the framework of the Jackiw-Telteiboim model to the bidimensional gravity. The resulting model shows that the quantum corrections…
In this paper we show how quantum corrections, although perturbatively small, may play an important role in the analysis of the existence of some classical models. This, in fact, appears to be the case of static, uniform--density models of…
The $\alpha'$-complete cosmology developed by Hohm and Zwiebach classifies the ${\rm O}(d,d;{\mathbb R})$ invariant theories involving metric, $b$-field and dilaton that only depend on time, to all orders in $\alpha'$. Some of these…
We compute the first-order $\alpha'$ corrections to a family of 4-dimensional, 4-charge, non-extremal black hole solutions of Heterotic Supergravity in the case with 3 independent charges. The solutions are fully analytic, reproduce the…
We review a few off-the-beaten-track ideas in cosmology. They solve a variety of fundamental problems; also they are fun. We start with a description of non-singular dilaton cosmology. In these scenarios gravity is modified so that the…
After introducing gauge-invariant cosmological perturbation theory we give an improved set of governing equations for multiple fluids including energy transfer. Having defined adiabatic and entropic perturbations we derive the…
As a most promising candidate for quantum theory of the gravity, the superstring theory has attracted many researchers including cosmologists. It is expected that the cosmological initial singularity is avoided within the context of the…
A broad class of two-dimensional loop-corrected dilaton gravity models exhibit cosmological solutions that interpolate between the string perturbative vacuum and a background with asymptotically flat metric and linearly growing dilaton. The…
We study time-dependent backgrounds in the low energy regimes of string theories. In particular the emphasis is on the general study of exotic phenomena such as positive acceleration and gravitational bounces. We generalize the usual…
We construct exact, time-dependent, black hole solutions of Einstein-Maxwell-dilaton theory with arbitrary dilaton coupling, $a$. For $a=1$ this theory arises as the four-dimensional low-energy effective description of heterotic string…
In a class of non-singular cosmologies derived from higher-order corrections to the low-energy bosonic string action, we derive evolution equations for the most general cosmological scalar, vector and tensor perturbations. In the large…
We review some aspects of the non-perturbative formulation of 2-dim. string theory in terms of non-relativistic fermions. We derive the bosonization using $W_\infty$ coherent states in the path-integral formulation. We discuss the classical…
This work develops a new method to calculate non-perturbative corrections in one-dimensional Quantum Mechanics, based on trans-series solutions to the refined holomorphic anomaly equations of topological string theory. The method can be…
The Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) black hole is an influential solution of the low energy heterotic string theory. As it is well known, it presents a singular extremal limit. We construct a regular extension of the…
Although the cosmological perturbations with inverse-volume corrections from loop quantum cosmology have been studied using the anomaly-free algebra approach in much of the literature, there still remains an important issue that some…
The influence of higher order (stringly inspired) curvature corrections to the classical General Relativity spherically symmetric solution is studied. In string gravity these curvature corrections have a special form and can provide a…
In this talk we discuss the cosmic singularity. We motivate the need to correct general relativity in the study of singularities, and mention the kind of corrections provided by string theory. We review how string theory resolves time-like…
We study the time evolution of a $3+1$ dimensional spacetime, where space is a large three-sphere, due to small perturbations of the background fields. We focus on two classes of deformations. One corresponds on the worldsheet to…
It is shown that new leading ($\al'$) as well as all-order solutions of String theory can be obtained by taking appropriate singular limits of the known solutions. We give several leading order solutions for the bosonic as well as the…
We present a combined analytical and numerical study of the effective action of field theory cosmic strings in the Abelian-Higgs model in flat space. Starting directly from the underlying solitonic field theory description, we provide a…