Are Glueballs Knotted Closed Strings?

TL;DR

This paper proposes that glueballs can be modeled as knotted closed strings with twist, explaining their degeneracy and matching experimental data, and explores their interactions and implications for extra dimensions.

Contribution

It introduces a string-theoretic model of glueballs as knotted closed strings with twist, linking their stability, degeneracy, and experimental signatures to Yang-Mills theory.

Findings

Degenerate glueball spectrum explained by twisted closed strings.

Identification of $ ext{eta}_L(1410)$ as a $0^{-+}$ glueball.

Shared production ratios support similar structures of glueball states.

Abstract

Glueballs have a natural interpretation as closed strings in Yang-Mills theory. Their stability requires that the string carries a nontrivial twist, or then it is knotted. Since a twist can be either left-handed or right-handed, this implies that the glueball spectrum must be degenerate. This degeneracy becomes consistent with experimental observations, when we identify the $\eta_L(1410)$ component of the $\eta(1440)$ pseudoscalar as a $0^{-+}$ glueball, degenerate in mass with the widely accepted $0^{++}$ glueball $f_0(1500)$. In addition of qualitative similarities, we find that these two states also share quantitative similarity in terms of equal production ratios, which we view as further evidence that their structures must be very similar. We explain how our string picture of glueballs can be obtained from Yang-Mills theory, by employing a decomposed gauge field. We also consider various experimental consequences of our proposal, including the interactions between glueballs and quarks and the possibility to employ glueballs as probes for extra dimensions: The coupling of strong interactions to higher dimensions seems to imply that absolute color confinement becomes lost.