Glueballs: hadrons without quarks
Abstract
Glueballs are colour-singlet bound states built from gluons alone. They are an unavoidable consequence of the non-Abelian structure of Quantum Chromodynamics (QCD), and, in the pure Yang--Mills limit, they are the only physical excitations of the theory. The present article reviews what is known about them. After establishing which spin, parity and charge-conjugation quantum numbers two- and three-gluon states can carry, the pure-gauge spectrum is surveyed. Each of the main theoretical approaches and their respective conclusions are briefly presented. They include lattice QCD, constituent-gluon and Coulomb-gauge models, functional Dyson--Schwinger and Bethe--Salpeter equations, holographic models, and QCD sum rules. Particular attention is paid to the scale-setting ambiguity that limits how precisely a quenched glueball mass can be converted into physical units. The discussion then turns to full QCD. After discussing the meaning of a glueball assignment in this context, unquenching effects and questions related to glueball--qq̅ mixing are addressed. The large-Nc counting that underpins the mixing picture, as well as mass-matrix and effective-Lagrangian treatments of mixing are presented. The selection rules and dynamical mechanisms that shape glueball decays are also discussed. The gluon-rich production mechanisms used experimentally are finally reviewed. The candidates are assessed sector by sector: f0(1370)/f0(1500)/f0(1710) and the competing interpretations of the scalar sector, $η(1405)/η(1475)$ and X(2370) in the pseudoscalar sector, the crowded tensor region, and the essentially unexplored C=−1 sector and its connection to the Odderon. Outlooks on the programmes that could help in validating some of these candidates or identifying others are reviewed as a conclusion.
Related
- Improving hadron creation operators for charmonium, glueballs and baryons
- Glueballs and fractional anomalous determinants at nonzero θ, and the decays of the X(2370)
- Large N hadron scattering bootstrap: massive pions and glueballs
- Effective field theory of scalar glueballs: Form factors and interaction radii
- Instanton liquid framework for non-perturbative QCD in light hadrons
BibTeX
@misc{chevalier2026glueballs,
title = {{Glueballs: hadrons without quarks}},
author = {Cyrille Chevalier and Vincent Mathieu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.16790},
eprint = {2609.16790},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.16790},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Glueballs: hadrons without quarks
AU - Cyrille Chevalier
AU - Vincent Mathieu
PY - 2026
DA - 2026/09/15
PB - arXiv
DO - 10.48550/arxiv.2609.16790
UR - https://arxiv.org/abs/2609.16790
AB - Glueballs are colour-singlet bound states built from gluons alone. They are an unavoidable consequence of the non-Abelian structure of Quantum Chromodynamics (QCD), and, in the pure Yang--Mills limit, they are the only physical excitations of the theory. The present article reviews what is known about them. After establishing which spin, parity and charge-conjugation quantum numbers two- and three-gluon states can carry, the pure-gauge spectrum is surveyed. Each of the main theoretical approaches and their respective conclusions are briefly presented. They include lattice QCD, constituent-gluon and Coulomb-gauge models, functional Dyson--Schwinger and Bethe--Salpeter equations, holographic models, and QCD sum rules. Particular attention is paid to the scale-setting ambiguity that limits how precisely a quenched glueball mass can be converted into physical units. The discussion then turns to full QCD. After discussing the meaning of a glueball assignment in this context, unquenching effects and questions related to glueball--qq̅ mixing are addressed. The large-N_c counting that underpins the mixing picture, as well as mass-matrix and effective-Lagrangian treatments of mixing are presented. The selection rules and dynamical mechanisms that shape glueball decays are also discussed. The gluon-rich production mechanisms used experimentally are finally reviewed. The candidates are assessed sector by sector: f_0(1370)/f_0(1500)/f_0(1710) and the competing interpretations of the scalar sector, $η(1405)/η(1475)$ and X(2370) in the pseudoscalar sector, the crowded tensor region, and the essentially unexplored C=−1 sector and its connection to the Odderon. Outlooks on the programmes that could help in validating some of these candidates or identifying others are reviewed as a conclusion.
ER -