Inflation with blowing-up solution of cosmological constant problem

TL;DR

This paper explores a novel approach to the cosmological constant problem by blowing up a singular point into a parameter band, enabling inflationary solutions and a transition to standard cosmology.

Contribution

It introduces weak self-tuning solutions that transform the cosmological constant problem into a band of parameters, facilitating inflation and a natural exit to Big Bang cosmology.

Findings

Weak self-tuning solutions allow de Sitter space only outside a parameter band.

These solutions enable an inflationary phase without fine-tuning.

Hybrid inflation at the brane provides a mechanism to exit inflation and enter standard cosmology.

Abstract

The cosmological constant problem is how one chooses, without fine-tuning, one singular point $\Lambda_{eff}=0$ for the 4D cosmological constant. We argue that some recently discovered {\it weak self-tuning} solutions can be viewed as blowing-up this one point into a band of some parameter. These weak self-tuning solutions may have a virtue that only de Sitter space solutions are allowed outside this band, allowing an inflationary period. We adopt the hybrid inflation at the brane to exit from this inflationary phase and to enter into the standard Big Bang cosmology.