Holographic motivations and observational evidence for decreasing dark energy

TL;DR

This paper discusses holographic models with decreasing dark energy, showing observational evidence for dark energy evolution over cosmic time, and explores the connection between these models and underlying conformal field theories.

Contribution

It reviews theoretical holographic models predicting decreasing dark energy and presents observational evidence supporting this evolution, linking cosmological data with holographic CFT physics.

Findings

Observational data favor a decreasing dark energy component.

Likelihood analysis indicates negative potential slope with 99.99% confidence.

Potential variation of 36% over redshift range z<2.

Abstract

Negative lambda gravitational effective field theories dual to holographic CFTs have potentially realistic cosmological solutions. Generic cosmological solutions of these effective field theories have scalar field evolution that can lead to a period of accelerated expansion when the scalar field is at positive values of its potential (Fig. 1). If such a model describes our universe, significant evolution of dark energy is expected over a Hubble time as the scalar descends from positive to negative values of its potential towards the AdS extremum. Our recent observational study 2305.04946 based on supernova and baryon acoustic oscillation (BAO) observations suggests that significant evolution of dark energy associated with a descending scalar field may be preferred by data (Fig. 2). Taking a linear approximation to the scalar potential around the present value, a standard likelihood analysis gives an $e^{- \chi^2/2}$ distribution in which $dV/dt$ is presently negative in $99.99 \%$ of the distribution, with a mean fractional variation of the potential of $36 \%$ over the period $z \lessapprox 2$ over which supernova data is available. In this note, we review these theoretical and observational results and provide an update on the question of how the physics of these cosmological solutions can be related to the physics of the underlying CFT.