Betwixt Annihilation and Decay: The Hidden Structure of Cosmological Stasis

TL;DR

This paper uncovers a universal energy-flow structure underlying cosmological stasis phenomena, explaining how different theories with matter, radiation, and vacuum energy can exhibit fixed abundance ratios without fine-tuning.

Contribution

It reveals a common energy-flow framework that explains the emergence of stasis across various beyond Standard Model cosmologies, linking decay and annihilation processes.

Findings

Identifies a shared energy-flow structure in diverse stasis theories

Shows that stasis arises from a balance between decay and annihilation processes

Provides a unified understanding of cosmological attractors in BSM models

Abstract

Stasis is a unique cosmological phenomenon in which the abundances of different energy components in the universe (such as matter, radiation, and vacuum energy) each remain fixed even though they scale differently under cosmological expansion. Moreover, extended epochs exhibiting stasis are generally cosmological attractors in many BSM settings and thus arise naturally and without fine-tuning. To date, stasis has been found within a number of very different BSM cosmologies. In some cases, stasis emerges from theories that contain large towers of decaying states (such as theories in extra dimensions or string theory). By contrast, in other cases, no towers of states are needed, and stasis instead emerges due to thermal effects involving particle annihilation rather than decay. In this paper, we study the dynamics of the energy flows in all of these theories during stasis, and find that these theories all share a common energy-flow structure which in some sense lies between particle decay and particle annihilation. This structure has been hidden until now but ultimately lies at the root of the stasis phenomenon, with all of the previous stases appearing as different manifestations of this common underlying structure. This insight not only allows us to understand the emergence of stasis in each of these different scenarios, but also provides an important guide for the potential future discovery of stasis in additional cosmological systems.