Color Confinement and Screening in the θ Vacuum of QCD

Dmitri E. Kharzeev, Eugene M. Levin

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QCD perturbation theory ignores the compact nature of the SU(3) gauge group that gives rise to the periodic θ vacuum of the theory. We propose to modify the gluon propagator to reconcile perturbation theory with the anomalous Ward identities for the topological current in the θ vacuum. As a result, the gluon couples to the Veneziano ghost describing the tunneling transitions between different Chern-Simons sectors of the vacuum; we call the emerging gluon dressed by ghost loops a "glost." We evaluate the glost propagator and find that it has the form G(p) = (p2 + χtop/p2)-1 where χtop is the Yang-Mills topological susceptibility related to the η′ mass by the Witten-Veneziano relation; this propagator describes the confinement of gluons at distances ∼ χtop-1/4 ≃ 1 fm. The same functional form of the propagator was originally proposed by Gribov as a solution to the gauge copies problem that plagues perturbation theory. The resulting running coupling coincides with the perturbative one at p2 蠑 √χtop, but in the infrared region either freezes (in pure Yang-Mills theory) or vanishes (in full QCD with light quarks), in accord with experimental evidence. Our scenario makes explicit the connection between confinement and topology of the QCD vacuum; we discuss the implications for spin physics, high energy scattering, and the physics of quark-gluon plasma.

Original languageEnglish
Article number242001
JournalPhysical Review Letters
Issue number24
StatePublished - 16 Jun 2015


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