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Jeff Greensite

Publications and source records attributed to Jeff Greensite.

64 records · Page 4Linked to original sources
arXiv2009

Aspects of Confinement in Coulomb Gauge

I present some new results regarding confinement as it appears in Coulomb gauge. It is found that: i) a recently proposed Yang-Mills vacuum wavefunctional in temporal gauge and 2+1 dimensions yields a Coulomb-gauge ghost propagator and linear Coulomb potential in good agreement with lattice Monte Carlo results; ii) adding a few constituent gluons to heavy quark-antiquark states brings the interaction energy much closer to that of the static quark potential, and suggests the beginnings of gluon-chain formation at roughly one fermi; iii) a perturbative approach to Faddeev-Popov eigenvalues indicates that the zero eigenvalue at the Gribov horizon may occur either at, or away from, p=0, depending on the gauge choice and spacetime dimension. This last result may be relevant to the qualitatively different infrared behavior of the ghost propagator in Coulomb and Landau gauges.

hep-lat↗
arXiv2008

Center Vortices and the Dirac Spectrum

We study correlations between center vortices and the low-lying eigenmodes of the Dirac operator, in both the overlap and asqtad formulations. In particular we address a puzzle raised some years ago by Gattnar et al. [Nucl. Phys. B 716, 105 (2005)], who noted that the low-lying Dirac eigenmodes required for chiral symmetry breaking do not appear to be present in center-projected configurations. We show that the low-lying modes are in fact present in the staggered (asqtad) formulation, but not in the overlap and ``chirally improved'' formulations, and suggest a reason for this difference. We also confirm and extend the results of Kovalenko et al. [Phys. Lett. B 648, 383 (2007)], showing that there is a correlation between center vortex locations, and the scalar density of low-lying Dirac eigenmodes derived from unprojected configurations. This correlation is strongest at points which are associated, in the vortex picture, with non-vanishing topological charge density, such as vortex intersection and ``writhing'' points. We present supporting evidence that the lowest Dirac eigenmodes, in both asqtad and overlap formulations, have their largest concentrations in point-like regions, rather than on submanifolds of higher dimensionality.

hep-lat↗
arXiv2005

Gribov horizon under the (lattice) microscope

The infinite color-Coulomb energy of color-charged states is related to enhanced density of near-zero modes of the Faddeev-Popov operator in Coulomb gauge. We confirm the enhancement in numerical simulations and show that it is tied to the presence of percolating center vortex configurations.

hep-lat↗
arXiv2005

Center Vortices and the Gribov Horizon

We show how the infinite color-Coulomb energy of color-charged states is related to enhanced density of near-zero modes of the Faddeev-Popov operator, and calculate this density numerically for both pure Yang-Mills and gauge-Higgs systems at zero temperature, and for pure gauge theory in the deconfined phase. We find that the enhancement of the eigenvalue density is tied to the presence of percolating center vortex configurations, and that this property disappears when center vortices are either removed from the lattice configurations, or cease to percolate. We further demonstrate that thin center vortices have a special geometrical status in gauge-field configuration space: Thin vortices are located at conical or wedge singularities on the Gribov horizon. We show that the Gribov region is itself a convex manifold in lattice configuration space. The Coulomb gauge condition also has a special status; it is shown to be an attractive fixed point of a more general gauge condition, interpolating between the Coulomb and Landau gauges.

hep-lat↗
arXiv2004

Confinement and center vortices in Coulomb gauge: analytic and numerical results

We review the confinement scenario in Coulomb gauge. We show that when thin center vortex configurations are gauge transformed to Coulomb gauge, they lie on the common boundary of the fundamental modular region and the Gribov region. This unifies elements of the Gribov confinement scenario in Coulomb gauge and the center-vortex confinement scenario. We report on recent numerical studies which support both of these scenarios.

hep-lat↗
arXiv2004

Coulomb Energy, Remnant Symmetry, and the Phases of Non-Abelian Gauge Theories

We show that the confining property of the one-gluon propagator, in Coulomb gauge, is linked to the unbroken realization of a remnant gauge symmetry which exists in this gauge. An order parameter for the remnant gauge symmetry is introduced, and its behavior is investigated in a variety of models via numerical simulations. We find that the color-Coulomb potential, associated with the gluon propagator, grows linearly with distance both in the confined and - surprisingly - in the high-temperature deconfined phase of pure Yang-Mills theory. We also find a remnant symmetry-breaking transition in SU(2) gauge-Higgs theory which completely isolates the Higgs from the (pseudo)confinement region of the phase diagram. This transition exists despite the absence, pointed out long ago by Fradkin and Shenker, of a genuine thermodynamic phase transition separating the two regions.

hep-lat↗
arXiv2003

Center Dominance in SU(2) Gauge-Higgs Theory

We study the SU(2) gauge-Higgs system in D=4 dimensions, and analyze the influence of the fundamental-representation Higgs field on the vortex content of the gauge field. It is shown that center projected Polyakov lines, at low temperature, are finite in the infinite volume limit, which means that the center vortex distribution is consistent with color screening. In addition we confirm and further investigate the presence of a "Kertesz-line" in the strong-coupling region of the phase diagram, which we relate to the percolation properties of center vortices. It is shown that this Kertesz-line separates the gauge-Higgs phase diagram into two regions: a confinement-like region, in which center vortices percolate, and a Higgs region, in which they do not. The free energy of the gauge-Higgs system, however, is analytic across the Kertesz line.

hep-lat↗
arXiv2002

Proceedings to the Workshops ''What comes beyond the Standard model'' 2000,2001, VOLUME 1: Festschrift dedicated to the 60th birthday of Holger Bech Nielsen

The present volume is the collection of contributions by friends of Holger Bech Nielsen for his 60th birthday. Contents: 1.Unified internal space of spins and charges (N. Mankoc Borstnik) 2.Semitopological Q-Rings (M. Axenides) 3.Non-local axial anomalies in the Standard model (D. Melikhov, B. Stech) 4.Could there be a fourth generation? (C.D. Froggatt) 5.Another complex Bateman equation (D.B. Fairlie) 6.Non-associative loops for Holger Bech Nielsen (P.H. Frampton) 7.Particles, fluids and vortices (J.W. van Holten) 8.Results on 2D current algebras (J.L. Petersen) 9.Phase transition in gauge theories and the Planck scale physics (L.V. Laperashvili and D.A. Ryzhikh) 10.Some remarks on the 'classical' large N limit (P. Olesen) 11.String theory and the size of hadrons (L. Susskind) 12.Relativity and $c/sqrt3$ (S.I. Blinnikov, L.B. Okun and M.I. Vysotsky) 13.Vortices (Jeff Greensite)

hep-ph↗
arXiv2000

Center vortices in MCG - finite-size and gauge-copy effects

In SU(2) lattice gauge theory in maximal center gauge, we investigate the dependence of center-projected Creutz ratios and the vortex density on lattice size and the number of gauge copies. The dependence on the number of copies is rather strong on small lattices, but almost disappears on lattices sufficiently large compared to the expected average vortex thickness. The center-projected string tension, evaluated on sufficiently large lattices, is in good agreement with the full asymptotic string tension, and the vortex density scales according to the second-order asymptotic-freedom formula.

hep-lat↗