One-quark state near a boundary of the confinement phase of QCD

TL;DR

This paper introduces a novel bound state called 'quarkiton' near a boundary in QCD's confinement phase, showing it is confined by an attractive potential and exhibits partial confinement, with potential implications for phase interfaces.

Contribution

The study presents the theoretical and numerical discovery of a new one-quark bound state near a boundary in QCD, termed 'quarkiton,' with unique confinement properties.

Findings

Quarkitons are confined to a mirror boundary with a Cornell-type potential.

The string tension between the quark and mirror is lower than the fundamental string tension.

Quarkitons can exist at phase interfaces, similar to surface excitons in materials.

Abstract

We discuss a one-quark state in the confinement phase near a reflective chromometallic boundary both at finite and zero temperature. Using numerical simulations of lattice Yang-Mills theory, we show that the test quark is confined to the neutral mirror by an attractive potential of the Cornell type, suggesting the existence of a mirror-bound one-quark state, a "quarkiton." Surprisingly, the tension of the string spanned between the quark and the mirror is lower than the fundamental string tension. The quarkiton state exhibits a partial confinement: while the quark is localized in the vicinity of the mirror, it can still travel freely along it. Such quarkiton states share similarity with the surface excitons in metals and semiconductors that are bound to their negatively charged images at a boundary. The quarkitons can exist at the hadronic side of the phase interfaces in QCD that arise, for example, in the thermodynamic equilibrium of vortical quark-gluon plasma.