Ward–Green–Takahashi identities and the axial-vector vertex

Qin, Si‐xue; Roberts, Craig D.; Schmidt, S.

doi:10.1016/j.physletb.2014.04.041

Cited by 79 publications

(85 citation statements)

References 75 publications

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“…Consequently, at this stage we hesitate to draw any firm physical conclusions based on the size ofQ ∆ + . Instead we merely observe that bound-state solutions obtained using rainbow-ladder (RL) truncation typically underestimate the size of DCSB-induced angular momentum correlations [75,[118][119][120][121][122]. In contrast, our formulation of the Faddeev equation and current, based on propagator parametrisations and vertices fitted to empirical information [123,124], implicitly includes effects that transcend the RL truncation.…”

Section: Approachmentioning

confidence: 87%

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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Section: Approachmentioning

confidence: 87%

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

et al. 2014

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“…It is known that DCSB places severe constraints on the wave function of the ground-state pion [34,35]; but our last few observations emphasise, via Eq. (1), that it must also impose extraordinary constraints on the chirallimit wave function for every excited-state pseudoscalar meson.…”

Section: M5mentioning

confidence: 88%

“…This result follows from the general form of the Gell-Mann-Oakes-Renner relation for isospin-nonzero pseudoscalars [33][34][35]:…”

Section: Introductionmentioning

confidence: 83%

Distribution amplitudes of radially-excitedπandKmesons

Chang

Gao

et al. 2016

Phys. Rev. D

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A symmetry-preserving truncation of the two-body bound-state problem in relativistic quantum field theory is used to compute the leading-twist parton distribution amplitudes (PDAs) for the first radial excitations of the π-and K-mesons. In common with ground states in these channels, the PDAs are found to be dilated with respect to the relevant conformal-limit form and skewed toward the heavier valence-quark in asymmetric systems. In addition, the PDAs of radially-excited pseudoscalar mesons are not positive definite, owing to the fact that dynamical chiral symmetry breaking (DCSB) forces the leptonic decay constant of such states to vanish in the chiral limit. These results highlight that DCSB is expressed visibly in every pseudoscalar meson constituted from light-quarks. Hence, so long as its impact is empirically evident in the pseudoscalar members of a given spectrum level, it is unlikely that chiral symmetry is restored in any of the hadrons that populate this level.

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“…Here M(q, p; P ) is the renormalized, fully amputated, two particle irreducible, quark-antiquark scattering kernel. It is related to K via the Axialvector Ward-Takahashi identity [74,75].…”

Section: Sde-bse Approachmentioning

confidence: 99%