Bumblebee field as a source of cosmological anisotropies

TL;DR

This paper explores how a bumblebee field, which violates Lorentz symmetry, can generate cosmological anisotropies within a Bianchi I universe, potentially explaining observed CMB anisotropies.

Contribution

It introduces a model where a bumblebee field causes anisotropies in the universe, linking Lorentz violation to observable cosmic microwave background features.

Findings

Bumblebee field induces preferred axis in cosmology.

Upper bounds on bumblebee field strength from CMB quadrupole and octopole.

Lorentz violation contributes to cosmic anisotropies.

Abstract

In this work, a bumblebee field is adopted in order to generate cosmological anisotropies. For that purpose, we assume a Bianchi I cosmology, as the background geometry, and a bumblebee field coupled to it. Bumblebee models are examples of a mechanism for the Lorentz symmetry violation by assuming a nonzero vacuum expectation value for the bumblebee field. When coupled to the Bianchi I geometry, which is not in agreement with a cosmological principle, the bumblebee field plays the role of a source of anisotropies and produces a preferred axis. Thus, a fraction of the cosmic anisotropies would come from the Lorentz symmetry violation. In the last part of the article, we try to assume an upper bound on the bumblebee field using the quadrupole and octopole moments of the cosmic microwave background radiation.