Inflation from higher dimensions

TL;DR

This paper derives a scalar potential from an eight-dimensional modified gravity model with flux compactification, demonstrating a viable inflationary scenario with potential implications for higher-dimensional supergravity theories.

Contribution

It presents a novel derivation of a scalar potential from higher-dimensional modified gravity with flux compactification, enabling a realistic inflation model with stabilized moduli.

Findings

The scalar potential supports cosmological inflation with the scalaron as inflaton.

The volume modulus is nearly stabilized during inflation.

Potential connections to higher-dimensional supergravity theories.

Abstract

We derive the scalar potential in four spacetime dimensions from an eight-dimensional $(R+\gamma R^4-2\Lambda-F_4^2)$ gravity model in the presence of the 4-form $F_4$, with the (modified gravity) coupling constant $\gamma$ and the cosmological constant $\Lambda$, by using the flux compactification of four extra dimensions on a 4-sphere with the warp factor. The scalar potential depends upon two scalar fields: the scalaron and the 4-sphere volume modulus. We demonstrate that it gives rise to a viable description of cosmological inflation in the early Universe, with the scalaron playing the role of inflaton and the volume modulus to be (almost) stabilized at its minimum. We also speculate about a possibility of embedding our model in eight dimensions into a modified eight-dimensional supergavity that, in its turn, arises from a modified eleven-dimensional supergravity.