Thick DGP braneworlds

TL;DR

This paper investigates thick DGP braneworld models, revealing how finite brane thickness modifies cosmological dynamics, leading to early inflation and late-time acceleration driven by 5D effects, with implications for gravity leakage into extra dimensions.

Contribution

It introduces a finite thickness in DGP braneworlds, showing how this alters cosmological equations and affects the universe's expansion history compared to thin brane models.

Findings

Finite brane thickness modifies the standard DGP Friedmann equations.

Both early inflation and late-time acceleration are driven by 5D geometry effects.

Gravity transitions between 4D and 5D regimes depending on cosmological epoch.

Abstract

We study Dvali-Gabadadze-Porrati braneworlds with finite thickness. In respect to standard (thin) DGP Friedmann equation, finite thickness of the brane causes a subtle modification of the cosmological equations that can lead to significant physical consequences. The resulting cosmology is governed by two length scales which are associated with the brane thickness and with the crossover length respectively. In this setup both early inflation and late-time acceleration of the expansion are a consequence of the 5D geometry. At early times, as well as at late times, 5D effects become dominant (gravity leaks into the extra dimension), while, at intermediate times, gravity is effectively 4D due to non-trivial physics occuring in standard (thin) DGP scenarios.