Bumblebee field as a source of cosmological anisotropies

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 geom-etry, 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.

Automated summary

In this work, a bumblebee field is utilized to generate cosmological anisotropies by violating Lorentz symmetry through a nonzero vacuum expectation value. When coupled to Bianchi I geometry, the bumblebee field produces a preferred axis, contributing to cosmic anisotropies. The article concludes by attempting to place an upper limit on the bumblebee field using the quadrupole and octopole moments of the cosmic microwave background radiation.