The Casimir Effect in (3+1)-dimensional lattice Yang-Mills theory at finite temperature: the unexpected universality of quarkiton and glueton boundary states

TL;DR

This paper investigates the Casimir effect in (3+1)-dimensional lattice Yang-Mills theory at finite temperature, revealing universal ratios between boundary and bulk states, and extending the understanding of nonperturbative boundary states near the deconfinement transition.

Contribution

It extends previous work by analyzing boundary states at finite temperature and uncovers a universal ratio linking boundary and bulk mass scales in Yang-Mills theory.

Findings

Identification of boundary states (gluonoton and quarkiton) at finite temperature.

Observation of a universal ratio between boundary and bulk mass scales.

Evidence that boundary states may have physical relevance through domain-wall realizations.

Abstract

In our earlier work on the Casimir effect in (3+1)-dimensional Yang-Mills theory, we identified two novel nonperturbative states arising in QCD with boundaries: the glueton and the quarkiton. The glueton, or "gluon exciton", is a colorless bound state formed by gluons interacting with their negatively colored images in a chromometallic mirror. The quarkiton, or "quark exciton", is a meson-like state comprising a heavy quark attracted to its image through the mirror. In this study, we extend our analysis to finite temperatures near the deconfinement phase transition $(T \approx 0.78 T_c)$, where we observe a linear potential between a color-neutral chromometallic mirror and a heavy test quark. Our result suggests that the quarkiton state can have a physical relevance since mirrors for photons and, presumably, gluons can be realized in field theories as domain-wall solutions. Furthermore, we find a striking universality: the ratio of the glueton mass to the bulk $0^{++}$ glueball mass - defining the bulk mass gap - matches the ratio of the quarkiton string tension to the string tension between quark and anti-quark in the absence of the mirror, with a value $\mathcal{R} = 0.294(11)$.