Study of Possible Proton-Antiproton Hexaquark State in Lattice QCD

TL;DR

This study uses lattice QCD to investigate the existence of a proton-antiproton hexaquark state, finding no evidence for a bound state near the physical quark masses.

Contribution

It provides the first lattice QCD analysis of the proton-antiproton hexaquark candidate, assessing its mass relative to the two-proton threshold.

Findings

Proton-antiproton is slightly above the 2m_p threshold for light quarks.

Lattice signals do not support a bound proton-antiproton hexaquark state.

Results are consistent with no stable spin-zero hexaquark in this system.

Abstract

We have used standard techniques of lattice quantum chromodynamics to look for evidence of the spin-zero six quark flavour singlet state ($J^{PC}=0^{-+}$) observed by BES Collaboration, and to determine the splitting between the mass of the possible proton-antiproton and the mass of two protons, its threshold. Using the various interpolating fields we find indications that for sufficiently light quarks proton-antiproton is slightly above the $2m_{p}$ threshold. The lattice resonance signal of binding observed near the physical and continuum regimes do not support the existence of proton-antiproton state as a spin-zero hexaquark state.