TY - JOUR

T1 - Color Confinement and Screening in the θ Vacuum of QCD

AU - Kharzeev, Dmitri E.

AU - Levin, Eugene M.

N1 - Publisher Copyright:
© 2015 American Physical Society.

PY - 2015/6/16

Y1 - 2015/6/16

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=84935078566&partnerID=8YFLogxK

U2 - 10.1103/PhysRevLett.114.242001

DO - 10.1103/PhysRevLett.114.242001

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AN - SCOPUS:84935078566

SN - 0031-9007

VL - 114

JO - Physical Review Letters

JF - Physical Review Letters

IS - 24

M1 - 242001

ER -