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Accepted · first revision · record

Title: Which observed scalar mesons contain the lightest glueball?
Plain: QCD predicts particles made only of gluons, called glueballs, with the lightest near 1.7 GeV. It mixes with ordinary quark-antiquark states, and which observed particles contain it is disputed.
Precise: Quenched lattice QCD places the $0++$ glueball near $1.7\,\mathrm{GeV}$. Among $f0(1370)$, $f0(1500)$, $f0(1710)$ and $f0(1770)$, determine the glueball content (mixing fractions with $n-\mathrm{nbar}$ and $s-\mathrm{sbar}$), using $J/\psi$ radiative decays, two-photon widths, decay branching ratios and lattice QCD with dynamical quarks. Answer: a mixing scheme consistent with all production and decay data.
Settled by: Lattice QCD scattering calculation of the isoscalar scalar channel with glueball operators at physical quark masses, combined with coupled-channel fits to BESIII and LHCb data.
Kind: phenomenon
Answer type: identification
References: (empty)
Literature status: contested
Status note: Coupled-channel analyses of BESIII radiative $J/\psi$ decay data (around 2021-2022) assigned the largest glueball fraction to states near $1.7\ \text{to}\ 1.9\,\mathrm{GeV}$, with amplitude-model dependence unresolved as of 2026.
Posed since: (empty)