Quark propagator in Landau and Laplacian gauges with overlap fermions

Zhang, J. B.; Bowman, Patrick O.; Coad, Ryan J.; Heller, Urs M.; Leinweber, Derek B.; Williams, Anthony G.

doi:10.1103/physrevd.71.014501

Cited by 38 publications

(42 citation statements)

References 43 publications

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“…The prediction was confirmed in recent simulations [32] of lattice-regularised quenched-QCD, 3 and the conditions under which pointwise agreement between DSE results and lattice simulations may be obtained have been explored [34,35,36]. The enhancement of M (p 2 ) is central to the appearance of a constituent-quark mass-scale and an existential prerequisite for Goldstone modes.…”

Section: Dressed-quark Propagatorsupporting

confidence: 61%

On Nucleon Electromagnetic Form Factors

et al. 2005

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Abstract. A Poincaré covariant Faddeev equation, which describes baryons as composites of confined-quarks and -nonpointlike-diquarks, is solved to obtain masses and Faddeev amplitudes for the nucleon and ∆. The amplitudes are a component of a nucleon-photon vertex that automatically fulfills the Ward-Takahashi identity for on-shell nucleons. These elements are sufficient for the calculation of a quark core contribution to the nucleons' electromagnetic form factors. An accurate description of the static properties is not possible with the core alone but the error is uniformly reduced by the incorporation of meson-loop contributions. Such contributions to form factors are noticeable for Q 2 2 GeV 2 but vanish with increasing momentum transfer. Hence, larger Q 2 experiments probe the quark core. The calculated behaviour of] GeV 2 agrees with that inferred from polarisation transfer data. Moreover, Q 2 F 2 (Q 2 )/F 1 (Q 2 ) ≈ constant on this domain. These outcomes result from correlations in the proton's amplitude. January 25, 2018

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Section: Dressed-quark Propagatorsupporting

confidence: 61%

On Nucleon Electromagnetic Form Factors

et al. 2005

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“…The enhancement of M (p 2 ) is central to the appearance of a constituent-quark mass-scale and an existential prerequisite for Goldstone modes. These DSE predictions are confirmed in numerical simulations of lattice-regularised QCD [145], and the conditions have been explored under which pointwise agreement between DSE results and lattice simulations may be obtained [146][147][148].…”

Section: A21 Dressed-quark Propagatorsupporting

confidence: 53%

Nucleon and $${\Delta}$$ Δ Elastic and Transition Form Factors

et al. 2014

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We present a unified study of nucleon and ∆ elastic and transition form factors, and compare predictions made using a framework built upon a Faddeev equation kernel and interaction vertices that possess QCD-like momentum dependence with results obtained using a symmetry-preserving treatment of a vector ⊗ vector contact-interaction. The comparison emphasises that experiments are sensitive to the momentum dependence of the running couplings and masses in the strong interaction sector of the Standard Model and highlights that the key to describing hadron properties is a veracious expression of dynamical chiral symmetry breaking in the bound-state problem. Amongst the results we describe, the following are of particular interest:possesses a zero at Q 2 = 9.5 GeV 2 ; any change in the interaction which shifts a zero in the proton ratio to larger Q 2 relocates a zero inthere is likely a value of momentum transfer above which G n E > G p E ; and the presence of strong diquark correlations within the nucleon is sufficient to understand empirical extractions of the flavour-separated form factors. Regarding the ∆(1232)-baryon, we find that, inter alia: the electric monopole form factor exhibits a zero; the electric quadrupole form factor is negative, large in magnitude, and sensitive to the nature and strength of correlations in the ∆(1232) Faddeev amplitude; and the magnetic octupole form factor is negative so long as rest-frame P -and D-wave correlations are included. In connection with the N → ∆ transition, the momentum-dependence of the magnetic transition form factor, G * M , matches that of G n M once the momentum transfer is high enough to pierce the meson-cloud; and the electric quadrupole ratio is a keen measure of diquark and orbital angular momentum correlations, the zero in which is obscured by meson-cloud effects on the domain currently accessible to experiment. Importantly, within each framework, identical propagators and vertices are sufficient to describe all properties discussed herein. Our analysis and predictions should therefore serve as motivation for measurement of elastic and transition form factors involving the nucleon and its resonances at high photon virtualities using modern electron-beam facilities.

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“…The classical theory's gauge invariance is then replaced by BRST symmetry [11,12], which can be used in perturbation theory to prove, e.g., renormalizability of quantum chromodynamics (QCD). Typically, however, the auxiliary condition meant to select a unique element from each class of equivalent configurations (a gauge field orbit) is nonperturbatively inadequate [1][2][3][4][5][6][7][8][9]. An unknown (probably infinite) number of configurations remain, each related to the identified element by a nonperturbative gauge transformation, and all contributing equally to the integral that should define the theory.…”

Section: Introductionmentioning

confidence: 99%

“…Except in particular cases [1][2][3][4][5][6][7][8][9], that cannot be completed consistently without adding ghost fields to the Lagrangian [10]. The classical theory's gauge invariance is then replaced by BRST symmetry [11,12], which can be used in perturbation theory to prove, e.g., renormalizability of quantum chromodynamics (QCD).…”

Section: Introductionmentioning

confidence: 99%

Locating the Gribov horizon

et al. 2018

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We explore whether a tree-level expression for the gluon two-point function, supposed to express effects of an horizon term introduced to eliminate the Gribov ambiguity, is consistent with the propagator obtained in simulations of lattice-regularized quantum chromodynamics (QCD). In doing so, we insist that the gluon two-point function obey constraints that ensure a minimal level of consistency with parton-like behavior on the ultraviolet domain. In consequence, we are led to a position which supports a conjecture that the gluon mass and horizon scale are equivalent emergent mass-scales, each with a value of roughly 0.5 GeV; and wherefrom it appears plausible that the dynamical generation of a running gluon mass may alone be sufficient to remove the Gribov ambiguity.

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Quark propagator in Landau and Laplacian gauges with overlap fermions

Cited by 38 publications

References 43 publications

On Nucleon Electromagnetic Form Factors

On Nucleon Electromagnetic Form Factors

Nucleon and $${\Delta}$$ Δ Elastic and Transition Form Factors

Locating the Gribov horizon

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