Coupled quintessence and vacuum decay

TL;DR

This paper investigates cosmological models where vacuum energy decays into dark matter, analyzing observational data to constrain these models and deriving a scalar field representation for further theoretical development.

Contribution

It provides observational constraints on vacuum decay models and introduces a coupled scalar field framework for these scenarios.

Findings

Vacuum decay models favor decay into dark matter only.

Observational data supports models with separately conserved baryons.

Derived a scalar field model for vacuum decay scenarios.

Abstract

We discuss observational consequences of a class of cosmological models characterized by the dilution of pressureless matter attenuated with respect to the usual $a^{-3}$ scaling due to the decay of vacuum energy. We carry out a joint statistical analysis of observational data from the new \emph{gold} sample of 182 SNe Ia, recent estimates of the CMB shift parameter, and BAO measurements from the SDSS to show that such models favor the decay of vacuum only into the dark matter sector, and that the separately conserved baryons cannot be neglected. In order to explore ways to more fundamentally motivated models, we also derive a coupled scalar field version for this general class of vacuum decay scenarios.