Anisotropic inflation and the origin of four large dimensions

Abstract

In the context of (4 + d)-dimensional general relativity, we propose an inflationary scenario wherein 3 spatial dimensions grow large, while d extra dimensions remain small. Our model requires that a self-interacting d-form acquire a vacuum expectation value along the extra dimensions.This causes 3 spatial dimensions to inflate, whilst keeping the size of the extra dimensions nearly constant. We do not require an additional stabilization mechanism for the radion, as stable solutions exist for flat, and for negatively curved compact extra dimensions. From a four-dimensional perspective, the radion does not couple to the inflaton; and, the small amplitude of the CMB temperature anisotropies arises from an exponential suppression of fluctuations, due to the higherdimensional origin of the inflaton. The mechanism triggering the end of inflation is responsible, both, for heating the universe, and for avoiding violations of the equivalence principle due to coupling between the radion and matter.

Accelerating Cosmologies and Inflation From M/Superstring Theories

“…Similar system of antisymmetric tensors and scalars is investigated in Ref. 64 for generating large four dimensions.…”

Three-form cosmology

“…Two-forms appear also in the framework of the asymmetric gravity [16] as the antisymmetric contribution to the metric, and have been considered in cosmology [17]. Forms, being intrinsically anisotropic, could be relevant for a dynamical origin of the four large dimensions [18], modelling Lorentz violation [19] or the observed CMB anomalies [20]. Form-driven inflation was suggested earlier this year [21,22].…”

Multidimensional cosmological models: Cosmological and astrophysical implications and constraints

“…See also Ref [25],. where a decoupling of scale factor excitations and inflaton was observed for a special solution subset of the Einstein equations.…”