Related papers: Cosmological Quantum String Vacua and String-Strin…
We study cosmological solutions to the low-energy effective action of heterotic string theory including possible leading order $\alpha'$ corrections and a potential for the dilaton. We consider the possibility that including such stringy…
The duality-type symmetries of string cosmology naturally lead to a pre-big-bang phase of accelerated evolution as dual counterpart of the decelerated expansion of standard cosmology. We discuss several properties of this scenario,…
We discuss how, in a Universe restricted to the causal region connected to the observer, General Relativity implies the quantum nature of physical phenomena and directly leads to a string theory scenario, whose dynamics is ruled by a…
We study string field theory (third quantization) of the two-dimensional model of quantum geometry called generalized CDT ("causal dynamical triangulations"). Like in standard non-critical string theory the so-called string field…
Several new results regarding the quantum cosmology of the quadratic gravity theory derived from the heterotic string effective action are presented. After describing techniques for solving the Wheeler-De Witt equation with appropriate…
We consider a toy cosmological model in string theory involving the winding and momentum modes of (m,n) strings, i.e. bound states of m fundamental and n D-strings. The model is invariant under S-duality provided that m and n are…
The definition of quantum singularity is extended from static space-times to conformally static space-times. After the usual definitions of classical and quantum singularities are reviewed, examples of quantum singularities in static…
We revisit the classical and quantum cosmology of a universe in which a self interacting scalar field is coupled to gravity with a flat FRW type metric undergoing continuous signature transition. We arrange for quantum cosmologically…
The cosmological constant problem and the compatibility of gravity with quantum mechanics are the two most pressing problems in all of gravitational theory. While string theory nicely addresses the latter, it has so far failed to provide…
We study the interaction of a massless quantized spinor field with the gravitational filed of N parallel static cosmic strings by using a perturbative approach. We show that the presence of more than one cosmic string gives rise to an…
We discuss some recent attempts to reconcile cosmology with supergravity and M/string theory. First of all, we point out that in extended supergravities the scalar masses are quantized in terms of the cosmological constant in de Sitter…
The observation of a scalar resonance at the LHC, compatible with perturbative electroweak symmetry breaking, reinforces the Standard Model parameterisation of all subatomic data. The logarithmic evolution of the SM gauge and matter…
This is a very brief survey of some results in the geometry of string duality delivered at a lecture given at ICM 1998, Berlin. String Duality is the statement that one kind of string theory compactified on one space is equivalent in some…
It is argued that classical string solutions should not be fine tuned to have a positive cosmological constant (CC) at the observed size, since even the quantum corrections from standard model effects will completely negate any classical…
Invited contribution to the Encyclopedia of Mathematical Physics (2nd edition), providing an overview over some main ideas and results in quantum cosmology. Key points: Canonical quantisation of homogeneous, isotropic cosmology; discussion…
The search for a theory of quantum gravity faces two great challenges: the incredibly small scales of the Planck length and time, and the possibility that the observed constants of nature are in part the result of random processes. A…
In addition to the familiar string theories with spacetime supersymmetry, there exist a number of non-supersymmetric ten-dimensional superstrings. Nearly all of these theories have closed string tachyons, indicating a misidentification of…
We discuss the main cosmological implications of considering string-loop effects and a potential for the dilaton in the lowest order string effective action. Our framework is based on the effective model arising from regarding homogeneous…
A string field theory(SFT) nonlocal model of the cosmological dark energy providing w<-1 is briefly surveyed. We summarize recent developments and open problems, as well as point out some theoretical issues related with others applications…
We study cosmic strings in the complex symmetron model, a scalar-tensor theory with a spontaneously broken local $U(1)$ symmetry in low matter density regions. Using numerical simulations, we show that these strings preferentially attach to…