Cosmological constant decaying with CMB temperature

Abstract

Recent observations of the dark energy density have demonstrated the fine-tuning problem and the challenges faced by theoretical modeling. In this study, we apply the self-similar symmetry (SSS) model, describing the hierarchical structure of the universe based on the Dirac large numbers hypothesis, to Einstein’s cosmological term. We introduce a new similarity dimension, [Formula: see text], in the SSS model. Using the [Formula: see text] SSS model, the cosmological constant [Formula: see text] is simply expressed as a function of the cosmic microwave background (CMB) temperature. The result shows that both the gravitational constant [Formula: see text] and [Formula: see text] are coupled with the CMB temperature, which simplifies the solution of Einstein’s field equations for the variable [Formula: see text]–[Formula: see text] model.

Cosmology from a running vacuum model driven by a scalar field

“…In Reference [58], a model with both decaying vacuum energy and dark matter was proposed. Besides, there are also studies concerning the decaying of the cosmological constant with the cosmic microwave background temperature [59].…”