Probing the Boundary of the Non-Perturbative QCD by Small Size Instantons
Edward Shuryak · arXiv (Cornell University) · 1999
The lattice data on the instanton size distribution suggest an additional O($ρ^2)$ action. The small-$ρ$ effect O($ρ^4)$ predicted by the Operator Product Expansion (OPE) is not observed. Similar deviations are also found for non-perturbative response to a small static color dipoles: it is O(r) not O(r$^2$). We suggest that small instanton radii in the QCD vacuum and small radii of the QCD strings (to which this observation relates) are consequences of the same phenomenon: a very robust dual superconductivity in the QCD vacuum, with relatively large Higgs VEV and surprisingly large Higgs mass.