Glueball instability and thermalization driven by dark radiation

TL;DR

This paper investigates how dark radiation influences glueball stability and thermalization in holographic gauge theories, revealing a phase transition from confinement to deconfinement as dark radiation density increases.

Contribution

It introduces a holographic model with dark radiation and demonstrates how increasing dark radiation causes glueball instability and triggers a confinement-deconfinement phase transition.

Findings

Glueball states are stable at low dark radiation levels.

Increasing dark radiation leads to glueball instability.

A critical dark radiation density induces a phase transition to a deconfined, thermalized state.

Abstract

We study glueballs in the holographic gauge theories living in a curved space-time. The dual bulk is obtained as a solution of the type IIB superstring theory with two parameters, which correspond to four dimensional (4D) cosmological constant $\lambda$ and the dark radiation $C$ respectively. The theory is in the confining phase for $\lambda <0$ and small $C$, then we observe stable glueball states in this theory. However, the stability of the glueball states is lost when the density of the dark radiation ($C$) increases and exceeds a critical point. Above this point, the dark radiation works as the heat bath of the Yang-Mills theory since the event horizon appears. Thus the system is thermalized, and the theory is in a finite temperature deconfinement phase, namely in the QGP phase. We observe this transition process through the glueball spectra which varies dramatically with $C$. We also examined the entanglement entropy of the system to find a clue of this phase transition and the role of the dark radiation $C$ in the entanglement entropy.