A Homogeneous and Isotropic Universe in Lorentz Gauge Theory of Gravity

TL;DR

This paper explores a Lorentz gauge theory of gravity, showing it predicts late-time acceleration without dark energy, relaxes constraints on vacuum energy, and allows inflation without slow-roll conditions.

Contribution

It introduces a homogeneous and isotropic universe model within Lorentz gauge gravity, revealing novel cosmological behaviors and relaxing key constraints compared to General Relativity.

Findings

Universe transitions from deceleration to acceleration at z~0.6 without dark energy

Vacuum energy constraints are relaxed in this theory

Inflation can occur without slow-roll conditions

Abstract

Lorentz gauge theory of gravity was recently introduced. We study the homogeneous and isotropic universe of this theory. It is shown that some time after the matter in the universe is diluted enough, at $z \sim 0.6$, the decelerating expansion shifts spontaneously to an accelerating one without a dark energy. We discuss that Lorentz gauge theory puts no constraint on the total energy content of the universe at present time and therefore the magnitude of vacuum energy predicted by field theory is not contradictory anymore. It is demonstrated that in this theory the limit on the number of relativistic particles in the universe is much looser than in GR. An inflationary mechanism is discussed as well. We show that the theory, unlike GR, does not require the slow-roll or similar conditions to drive the inflation at the beginning of the universe.