Inflation in the five-dimensional universe with an orbifold extra dimension

TL;DR

This paper constructs new inflationary solutions in a five-dimensional universe with an orbifold extra dimension, exploring effects of bulk and boundary cosmological constants on the inflationary dynamics.

Contribution

It provides explicit inflationary solutions in a simple five-dimensional orbifold model, including cases with non-zero bulk cosmological constant, extending previous work.

Findings

Solutions with static extra dimension and non-trivial background metric.

Inflation driven by bulk and boundary cosmological constants.

New solutions for non-zero bulk cosmological constant.

Abstract

New inflationary solutions to the Einstein equation are explicitly constructed in a simple five-dimensional model with an orbifold extra dimension $S^1/Z_2$. We consider inflation caused by cosmological constants for the five-dimensional bulk and the four-dimensional boundaries. In our solutions the extra dimension is static, and the background metric has a non-trivial configuration in the extra dimension. In addition to the solution for a vanishing bulk cosmological constant, which has already been discussed, we obtain solutions for a non-zero one.