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, 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.

A Checklist of Orchids Inside Dibrugarh University Campus, Assam, North-East India

“…This can have an impact on other fields' dynamics that are coupled to the Bumblebee field, while also maintaining geometric structures and conservation laws that are compatible with the standard pseudo-Riemannian manifold used in GR [16,17]. The simplest model with a single Bumblebee vector field B µ coupled to gravity in a non torsional spacetime can be described by the action [7,52],…”

“…In Ref. [52], the Bumblebee field is considered as a source of cosmological anisotropies. Another work of Bumblebee gravity on the Kesner metric has been found in Ref.…”

Gravitational traces of bumblebee gravity in metric–affine formalism

“…However, despite the non-Riemannian background, most studies in bumblebee gravity, for example, have been conducted within the metric approach of gravity, where the metric is the only dynamical geometric field. These investigations focus on obtaining exact solutions for different models that incorporate LSB in curved spacetimes, including bumblebee gravity [6][7][8][9][10][11][12][13], parity-violating models [14][15][16][17][18], and Chern-Simons modified gravity [19][20][21].…”

Spontaneous Lorentz symmetry breaking and one-loop effective action in the metric-affine bumblebee gravity

“…Among the models that consider LSB in curved space via the gravitational sector, special attention have received the Einstein-Aether theory [11], the Chern-Simons modified gravity [14], and the bumblebee gravity model [10]. The latter two theories, in particular, have been explored recently in a variety of different contexts, namely, in cosmology [15,16], black holes [17][18][19][20], and gravitational waves scenarios [21][22][23]. Moreover, degenerate higherorder scalar-tensor (DHOST) theories have been also deemed in LSB context [24].…”