Cosmological predictions from the Misner brane

TL;DR

This paper explores a five-dimensional brane cosmology model with Misner symmetry, deriving exact solutions for certain metrics, addressing horizon and flatness problems via extra-dimensional communication, and predicting observable CMB features consistent with current measurements.

Contribution

It introduces a Misner-brane framework that yields exact cosmological solutions, solves horizon and flatness problems through extra-dimensional effects, and predicts CMB anisotropies compatible with observations.

Findings

Exact solutions for Friedmann and black hole metrics on the brane.

Resolution of horizon and flatness problems via extra-dimensional communication.

Predicted CMB power spectrum with smaller secondary peaks matching observations.

Abstract

Within the spirit of five-dimensional gravity in the Randall-Sundrum scenario, in this paper we consider cosmological and gravitational implications induced by forcing the spacetime metric to satisfy a Misner-like symmetry. We first show that in the resulting Misner-brane framework the Friedmann metric for a radiation dominated flat universe and the Schwarzschild or anti-de Sitter black holes metrics are exact solutions on the branes, but the model cannot accommodate any inflationary solution. The horizon and flatness problems can however be solved in Misner-brane cosmology by causal and noncausal communications through the extra dimension between distant regions which are outside the horizon. Based on a semiclassical approximation to the path-integral approach, we have calculated the quantum state of the Misner-brane universe and the quantum perturbations induced on its metric by brane propagation along the fifth direction. We have then considered testable predictions from our model. These include a scale-invariant spectrum of density perturbations whose amplitude can be naturally accommodated to the required value 10$^{-5}-10^{-6}$, and a power spectrum of CMB anisotropies whose acoustic peaks are at the same sky angles as those predicted by inflationary models, but having much smaller secondary-peak intensities. These predictions seem to be compatible with COBE and recent Boomerang and Maxima measurements