Inflation from higher dimensions

Understand

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.