Quintessential Implications of the presence of AdS in the Dark Energy sector

TL;DR

This paper investigates the effects of a negative cosmological constant in the dark energy sector using current cosmological data, revealing theoretical and observational implications for cosmic evolution and quantum gravity.

Contribution

It introduces the inclusion of an AdS vacuum in dark energy models, demonstrating its compatibility with observations and its impact on the parameter space and cosmic lifetime.

Findings

AdS term allows a finite non-phantom region in DE parameter space

Negative cosmological constant implies a finite cosmic lifetime

Model remains consistent with DESI, supernovae, CMB, and weak-lensing data

Abstract

We explore the implications for an Anti-de Sitter (AdS) vacuum, equivalently a negative cosmological constant (nCC), in the dark energy (DE) sector using current cosmological observations. Our joint analysis uses DESI BAO, DESY5 supernovae, and P-ACT CMB (ACT-DR6 + Planck) measurements. We also use the KiDS weak-lensing measurement to cross-check consistency with the inferred value of $S_{8}$. Within the Chevallier--Polarski--Linder parametrization for the evolving component of the DE, the inclusion of an AdS term provides a theoretically motivated mechanism that opens up a finite non-phantom region in the CPL parameter space while remaining compatible with current observations. A negative cosmological constant also implies a finite cosmic lifetime, thereby linking observational DE phenomenology to broader questions in quantum gravity and string theory.