Mechanism for a decaying cosmological constant

Abstract

A mechanism is introduced to reduce a large cosmological constant to a sufficiently small value consistent with the observational upper limit. The basic ingradient in this mechanism is a distinction which has been made between the two unit systems used on cosmology and particle physics. We have used a conformal invariant gravitational model to define a particular conformal frame in terms of the large scale properties of the universe. It is then argued that the contributions of mass scales in particle physics to the vacuum energy density should be considered in a different conformal frame. In this manner a cancellation mechanism is presented in which the conformal factor plays a key role to relax the large effective cosmological constant. *

Cosmological constant in chameleon Brans–Dicke theory

“…Similarly, when ε > 0 the reverse is true, namely that matter is annihilated and the direction of energy transfer is outside of the matter system so that the rate of dilution is faster than the standard one. Even though β and ε in (22) are generally evolving functions, we consider the case that they can be regarded as constant parameters. The constancy of β means that we fix the arbitrary coupling function h(ϕ) to have an exponential form h(ϕ) = e β ϕ Mp .…”

“…This choice as a first approximation is more restrictive but greatly simplifies the mathematics and does not affect the basics of our arguments. In these cases, (22) reduces to ϕ M p = γ ln a…”

Gravitational coupling and dynamical reduction of the cosmological constant

“…Combining (8) and (11) leads to 12) where ψ 2 = α. Note that σ appears as a dynamical field which allows us to investigate the evolution ofm as the universe evolves.…”

Scale Transformation, Modified Gravity, and Brans-Dicke Theory

“…This usually leads to the variability of the fundamental constants. Recently, it is shown that one can use this dynamical distinction between two unit systems usually used in cosmology and particle physics to alleviate the cosmological constant and coincidence problems [7][8][9][10].…”