Natural constraints on the gluon-quark vertex

Binosi, Daniele; Chang, Lei; Papavassiliou, Joannis; Qin, Si‐xue; Roberts, Craig D.

doi:10.1103/physrevd.95.031501

Cited by 138 publications

(168 citation statements)

References 75 publications

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“…That form is not yet known, but recent work [69] has severely limited the class of realistic Ansätze by using just three physical constraints. This class may be expressed as follows (t = q + p):…”

Section: Flavor Dependence Of the Interactionmentioning

confidence: 99%

“…[69], involving two additional Dirac-matrix structures and hence two more coefficients. However, a 45 , a 8 and the associated tensors are by far the most important in connection with DCSB, and that is why we simplify the form.…”

Section: Flavor Dependence Of the Interactionmentioning

confidence: 99%

“…For a given value of n f , we solve the chiral-limit gap equation for every such vertex q Γ ν identified in Ref. [69] using the RGI running interaction, I (2,N f ) , described in Sec. 4.…”

Section: Flavor Dependence Of the Interactionmentioning

confidence: 99%

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Scale-setting, flavor dependence, and chiral symmetry restoration

2017

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We determine the flavour dependence of the renormalisation-group-invariant running interaction through judicious use of both unquenched Dyson-Schwinger equation and lattice results for QCD's gauge-sector two-point functions. An important step is the introduction of a physical scale setting procedure that enables a realistic expression of the effect of different numbers of active quark flavours on the interaction. Using this running interaction in concert with a well constrained class of dressed-gluon-quark vertices, we estimate the critical number of active lighter-quarks above which dynamical chiral symmetry breaking becomes impossible: n cr f ≈ 9; and hence in whose neighbourhood QCD is plausibly a conformal theory.Keywords: dynamical chiral symmetry breaking, Dyson-Schwinger equations, gluon-quark vertex, non-Abelian gauge-sector dynamics, numerical simulations of lattice-regularised QCD 1. Introduction. The last decade has seen the gauge sector of QCD provide important clues to some of the many puzzles encountered in the quest to understand the infrared (IR) dynamics of strongly-coupled theories. Of particular interest is the feature that the gluon propagator saturates at infrared momenta, i.e. ∆(k 2 0) = 1/m 2 g , m g 0.5 GeV [1-6], which entails that the long-range propagation characteristics of gluons are dramatically affected by their self-interactions. A similar feature is expressed in the dressed-quark propagator [7][8][9]; and, hence, it is now known that the Schwinger functions of both these elementary coloured excitations violate reflection positivity, a sufficient condition for confinement [10][11][12][13][14][15][16][17][18][19][20][21]. A consistent picture is thus beginning to emerge: strong dynamics generates IR cutoffs in QCD so that long-wavelength (λ 2/m g ∼ 1 fm) coloured-modes decouple and their role in hadron physics is superseded by interactions between light-hadrons [22][23][24][25].

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Section: Flavor Dependence Of the Interactionmentioning

confidence: 99%

Section: Flavor Dependence Of the Interactionmentioning

confidence: 99%

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Scale-setting, flavor dependence, and chiral symmetry restoration

2017

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“…Notwithstanding that off-shell Green's functions are not physical quantities, given their explicit dependence on the gauge-fixing parameter and the renormalization scheme, they encode valuable information on fundamental nonperturbative phenomena such as confinement, chiral symmetry breaking, and dynamical mass generation, and constitute the basic building blocks of symmetry-preserving formalisms intended to provide with a faithful description of hadron phenomenology (see, for instance [14][15][16][17][18][19]). …”

Section: Introductionmentioning

confidence: 99%

On the zero-crossing of the three-gluon Green’s function from lattice simulations

et al. 2018

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Abstract. We report on some efforts recently made in order to gain a better understanding of some IR properties of the 3-point gluon Green's function by exploiting results from large-volume quenched lattice simulations. These lattice results have been obtained by using both tree-level Symanzik and the standard Wilson action, in the aim of assessing the possible impact of effects presumably resulting from a particular choice for the discretization of the action. The main resulting feature is the existence of a negative logaritmic divergence at zero-momentum, which pulls the 3-gluon form factors down at low momenta and, consequently, yields a zero-crossing at a given deep IR momentum. The results can be correctly explained by analyzing the relevant Dyson-Schwinger equations and appropriate truncation schemes.

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“…Even though off-shell Green's functions are not physical quantities, given their explicit dependence on the gauge-fixing parameter and the renormalization scheme, they encode valuable information on fundamental nonperturbative phenomena such as confinement, chiral symmetry breaking, and dynamical mass generation, and constitute the basic building blocks of symmetrypreserving formalisms that aim at a veracious description of hadron phenomenology (see, for instance [13][14][15][16][17][18]). …”

Section: Introductionmentioning

confidence: 99%