Cosmological screening and the phantom braneworld model

TL;DR

This paper investigates how cosmological perturbations behave in the phantom braneworld model, revealing a screening effect that depends on a key parameter and approaches standard cosmology when this parameter is small.

Contribution

It provides explicit calculations of gravitational potentials in the phantom braneworld model, demonstrating a screening mechanism influenced by the model's parameters.

Findings

Gravitational potentials exhibit exponential screening behavior.

Screening length varies with the quasidensity parameter.

Model reduces to bcdm when a0Md0.

Abstract

The scalar and vector cosmological perturbations at all length scales of our Universe are studied in the framework of the phantom braneworld model. The model is characterized by the parameter $\Omega_M\equiv M^3/2m^2H_0$, with $M$ and $m$ the 5- and 4-dimensional Planck scales, respectively, and $H_0$ the Hubble parameter today, while $\Omega_M\rightarrow 0$ recovers the $\Lambda\rm CDM$ model. Ignoring the backreaction due to the peculiar velocities and also the bulk cosmological constant, allows the explicit computation of the gravitational potentials, $\Phi$ and $\Psi$. They exhibit exponentially decreasing screening behaviour characterized by a screening length which is a function of the quasidensity parameter $ \Omega_M$.