Goldstone boson's valence-quark distribution

Roberts, C. D.

doi:10.1016/s0920-5632(02)01333-6

Cited by 9 publications

(10 citation statements)

References 30 publications

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“…( 104) is still very much in evidence for current-quark masses as large as twice that of the squark. With this result our simple model reproduces a feature of more sophisticated DSE studies [53][54][55] and a numerical simulation of quenched lattice-QCD [57]. FIG.…”

Section: Dependence On the Current-quark Masssupporting

confidence: 69%

“…With this result we reproduce a feature of more sophisticated DSE studies [47][48][49] and a numerical simulation of quenched lattice-QCD [50].…”

Section: Dependence On the Current-quark Masssupporting

confidence: 62%

“…Then, so as to work with dimensionless quantities, we set m 60 = 0.06/ M qu ͑0͒ and, using Eqs. (39)- (49), require a leastsquares fit to 3…”

Section: B Numerical Resultsmentioning

confidence: 99%

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Aspects and consequences of a dressed-quark-gluon vertex

et al. 2004

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Features of the dressed-quark-gluon vertex and their role in the gap and Bethe-Salpeter equations are explored. It is argued that quenched lattice data indicate the existence of net attraction in the colour-octet projection of the quark-antiquark scattering kernel. This attraction affects the uniformity with which solutions of truncated equations converge pointwise to solutions of the complete gap and vertex equations. For current-quark masses less than the scale set by dynamical chiral symmetry breaking, the dependence of the dressed-quark-gluon vertex on the current-quark mass is weak. The study employs a vertex model whose diagrammatic content is explicitly enumerable. That enables the systematic construction of a vertex-consistent Bethe-Salpeter kernel and thereby an exploration of the consequences for the strong interaction spectrum of attraction in the colour-octet channel. With rising current-quark mass the rainbow-ladder truncation is shown to provide an increasingly accurate estimate of a bound state's mass. Moreover, the calculated splitting between vector and pseudoscalar meson masses vanishes as the current-quark mass increases, which argues for the mass of the pseudoscalar partner of the \Upsilon(1S) to be above 9.4 GeV. The absence of colour-antitriplet diquarks from the strong interaction spectrum is contingent upon the net amount of attraction in the octet projected quark-antiquark scattering kernel. There is a window within which diquarks appear. The amount of attraction suggested by lattice results is outside this domain.Comment: 22 pages, 12 figure

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Section: Dependence On the Current-quark Masssupporting

confidence: 69%

“…With this result we reproduce a feature of more sophisticated DSE studies [47][48][49] and a numerical simulation of quenched lattice-QCD [50].…”

Section: Dependence On the Current-quark Masssupporting

confidence: 62%

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Aspects and consequences of a dressed-quark-gluon vertex

et al. 2004

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“…These causal relationships emphasise again, following identical conclusions drawn from computations of the pion and nucleon valence-quark distributions [24,30,[55][56][57][58], that understanding parton distribution functions (PDFs), as opposed to merely parametrising them, rests upon grasping the nature of DCSB in QCD. It exposes the potential gains to be made in hadron physics by shifting theoretical focus from modelling PDFs to their wellconstrained computation.…”

Section: Quark Models and Gamentioning

confidence: 82%

Dressed quarks and the nucleon's axial charge

2013

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The nucleon's axial charge, gA, expresses features that are both fundamental to the strong interaction and crucial to its connection with weak interaction physics. We show that dynamical chiral symmetry breaking (DCSB) suppresses the axial-charge of a dressed-quark, g q A , at infrared momenta. Since this effect disappears as chiral symmetry is restored, one may argue that gA vanishes with the restoration of chiral symmetry because no nucleon bound-state survives the associated transition. The suppression of g q A is shown to be part of an explanation for a 25% reduction of gA from its nonrelativistic quark-model value. Critical too, however, is the presence of dressed-quark angular momentum within the nucleon. The value of g q A depends on the kernels of the gap and Bethe-Salpeter equations. We find that incorporation of essentially nonperturbative effects associated with DCSB into these kernels inflates the value relative to that obtained at leading-order in a widely used truncation of QCD's Dyson-Schwinger equations. Such corrections also affect the nucleon's axial radius. In both cases, however, agreement with experiment will require similar improvements to the Faddeev kernel and associated interaction current.

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“…This scheme underlies the successful application of a rainbow-ladder model to flavournonsinglet pseudoscalar mesons and vector mesons [2,3,4,5]. The systematic nature of the scheme has also made possible a proof of Goldstone's theorem in QCD [6] and the derivation of a mass formula that unifies the light-and heavy-quark sectors [10].…”

Section: Symmetry Preserving Truncationmentioning

confidence: 99%

Facets of confinement and dynamical chiral symmetry breaking

et al. 2003

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Abstract. The gap equation is a cornerstone in understanding dynamical chiral symmetry breaking and may also provide clues to confinement. A symmetry-preserving truncation of its kernel enables proofs of important results and the development of an efficacious phenomenology. We describe a model of the kernel that yields: a momentum-dependent dressed-quark propagator in fair agreement with quenched lattice-QCD results; and chiral limit values: f 0 π = 68 MeV and qq = − (190 MeV) 3 . It is compared with models inferred from studies of the gauge sector.

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Goldstone boson's valence-quark distribution

Cited by 9 publications

References 30 publications

Aspects and consequences of a dressed-quark-gluon vertex

Aspects and consequences of a dressed-quark-gluon vertex

Dressed quarks and the nucleon's axial charge

Facets of confinement and dynamical chiral symmetry breaking

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