Dark Matter from Dark Glueball Dominance

TL;DR

This paper explores a dark sector composed of dark gluons that confine into glueballs, analyzing their cosmological evolution, decay processes, and potential to account for dark matter within the early universe.

Contribution

It provides a detailed study of dark glueball dynamics, decay mechanisms, and their implications for dark matter and cosmology, highlighting the role of a dimension-6 connector operator.

Findings

Stable glueballs can account for dark matter abundance.

Constraints on dark sectors from overproduction and decay impacts.

Decay of lightest glueball can reheat the Standard Model.

Abstract

New gauge forces can play an important role in the evolution of the early universe. In this work we investigate the cosmological implications of a pure Yang-Mills dark sector that is dominantly populated after primordial inflation. Such a dark sector takes the form of a bath of dark gluons at high temperatures, but confines at lower temperatures to produce a spectrum of dark glueballs. These glueballs then undergo a freezeout process such that the remnant population is nearly completely dominated by the lightest state. To reproduce the observed cosmology, this lightest glueball species must decay to the Standard Model to repopulate and reheat it. At leading order, this can occur through a connector operator of dimension-6. In contrast, other glueballs can be parametrically long-lived or stable, and remain as contributors to dark matter or modify the observed cosmology through their later decays. In this work we study the evolution of such dark sectors in detail. We demonstrate that stable remnant glueballs can produce the measured dark matter abundance. We also derive broad constraints on non-Abelian dark sectors from overproduction of remnant glueballs when they are stable or from their destructive impact when they are able to decay.