Bumblebee field as a source of cosmological anisotropies

Abstract

In this work, a bumblebee field is adopted in order to generate cosmological anisotropies. For that purpose, weassume 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 byassuming a nonzero vacuum expectation value for the bumblebee field. When coupled tothe Bianchi I geometry, which is not in agreement with a cosmological principle, the bumblebee fieldplays the role of a source of anisotropies and produces a preferred axis. Thus, a fraction of the cosmic anisotropieswould come from the Lorentz symmetry violation.In the last part of the article, we try to assume an upper bound on the bumblebee field usingthe quadrupole and octopole moments of the cosmic microwave background radiation.