Correspondence between a decaying dark matter sector scenario and scalar field model

TL;DR

This paper models a decaying dark matter sector with a scalar field, revealing that physical viability leads to phantom dark energy behavior and proposing a complex scalar field interpretation to address late-time pathologies.

Contribution

It introduces a scalar field framework for decaying dark matter, demonstrating phantom behavior and a stable late-time attractor, with a novel complex scalar field interpretation.

Findings

Existence of a potential minimum implies phantom dark energy.

Complex scalar field mapping resolves late-time kinetic issues.

Phantom epoch is a stable late-time cosmic attractor.

Abstract

We explore the theoretical viability of modeling a decaying dark matter sector through a unified scalar field approach. Using exact analytical solutions of the Friedmann constraints, we map the fluid phenomenology onto a scalar field potential. Our analysis reveals that physical viability, specifically the existence of a well-defined potential minimum; inevitably forces the dark energy equation of state into the phantom domain. To resolve the kinetic pathologies at late times, we propose reinterpreting the framework within a complex scenario, mapping the imaginary transition to the angular dynamics of a $U(1)$ phase. This mapping naturally yields an ultra-light mass scale of $m_\phi \sim 10^{-33} \ \text{eV}$, classifying the model as a unified dark fluid. Finally, we employ a dynamical approach to study the effects of non-minimal coupling, proving that the phantom-dominated epoch acts as a stable, late-time cosmic attractor in this kind of cosmological scenario.