Classical Inhomogeneities in String Cosmology
نویسندگان
چکیده
We generalize previous work on inhomogeneous pre-big bang cosmology by including the effect of non-trivial moduli and antisymmetric-tensor/axion fields. The general quasi-homogeneous asymptotic solution—as one approaches the big bang singularity from perturbative initial data—is given and its range of validity is discussed, allowing us to give a general quantitative estimate of the amount of inflation obtained during the perturbative pre-big bang era. The question of determining early-time “attractors” for generic pre-big bang cosmologies is also addressed, and a motivated conjecture is advanced. We also discuss S-duality-related features of the solutions, and speculate on the way an asymptotic T-duality symmetry may act on moduli space as one approaches the big bang. PACS number(s): 11.25.-w, 98.80.Cq, 04.50.+h Typeset using REVTEX ∗Permanent address: Institute for Theoretical Physics, Hoża 69, 00-689 Warsaw, Poland. 1
منابع مشابه
The fate of classical tensor inhomogeneities in pre-big-bang string cosmology
In pre-big-bang string cosmology one uses a phase of dilaton-driven inflation to stretch an initial (microscopic) spatial patch to the (much larger) size of the big-bang fireball. We show that the dilaton-driven inflationary phase does not naturally iron out the initial classical tensor inhomogeneities unless the initial value of the string coupling is smaller than gin . 10 −35.
متن کاملSpherical Curvature Inhomogeneities in String Cosmology
We study the evolution of non-linear spherically symmetric inhomogeneities in string cosmology. Friedmann solutions of different spatial curvature are matched to produce solutions which describe the evolution of non-linear density and curvature inhomogeneities. The evolution of bound and unbound inhomogeneities are studied. The problem of primordial black hole formation is discussed in the stri...
متن کاملLinear Perturbations in Brane Gas Cosmology
Abstract We consider the effect of string inhomogeneities on the time dependent background of Brane Gas Cosmology. We derive the equations governing the linear perturbations of the dilatongravity background in the presence of string matter sources. We focus on long wavelength fluctuations and find that there are no instabilities. Thus, the predictions of Brane Gas Cosmology are robust against t...
متن کاملThe Cosmological Moduli Problem, Supersymme- Try Breaking , and Stability in Postinflationary Cos- Mology
We review scenarios that have been proposed to solve the cosmological problem caused by moduli in string theory, the Postmodern Polonyi Problem (PPP). In particular, we discuss the difficulties encountered by the apparently " trivial " solution of this problem, in which moduli masses are assumed to arise from nonperturbative, SUSY preserving, dynamics at a scale higher than that of SUSY breakin...
متن کاملRelaxed Bounds on the Dilaton Mass In a String Cosmology Scenario
We discuss bounds on the dilaton mass, following from the cosmological amplification of the quantum fluctuations of the dilaton background, under the assumption that such fluctuations are dominant with respect to the classical background oscillations. We show that if the fluctuation spectrum grows with the frequency the bounds are relaxed with respect to the more conventional case of a flat or ...
متن کامل2 1 0 Ju l 2 00 1 Hamilton - Jacobi approach to pre - big bang cosmology and the problem of initial conditions
The Hamilton-Jacobi equation for the string cosmology is solved using the gradient expansion method. The zeroth order solution is taken to be the standard pre-big bang model and the second order solution is found for the dilaton and the three-metric. It indicates that corrections generated by inhomogeneities of the seed metric are suppressed near the singularity and are growing towards the asym...
متن کامل