Unified description of hadron-photon and hadron-meson scattering in the Dyson-Schwinger approach

Eichmann, Gernot; Fischer, Christian

doi:10.1103/physrevd.85.034015

Cited by 24 publications

(26 citation statements)

References 73 publications

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“…In analogy to the form factor diagrams in Fig. 4.3 one can derive a closed nonperturbative expression for the CS amplitude and other scattering amplitudes at the quark level [691,692]. The onshell scattering amplitude M µν is the residue of the quark six-point function that is coupled to two external currents with qq quantum numbers: …”

Section: Verification Of the Discrepancymentioning

confidence: 99%

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Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

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421

530

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We review the spectrum and electromagnetic properties of baryons described as relativistic three-quark bound states within QCD. The composite nature of baryons results in a rich excitation spectrum, whilst leading to highly non-trivial structural properties explored by the coupling to external (electromagnetic and other) currents. Both present many unsolved problems despite decades of experimental and theoretical research. We discuss the progress in these fields from a theoretical perspective, focusing on nonperturbative QCD as encoded in the functional approach via Dyson-Schwinger and Bethe-Salpeter equations. We give a systematic overview as to how results are obtained in this framework and explain technical connections to lattice QCD. We also discuss the mutual relations to the quark model, which still serves as a reference to distinguish 'expected' from 'unexpected' physics. We confront recent results on the spectrum of non-strange and strange baryons, their form factors and the issues of two-photon processes and Compton scattering determined in the DysonSchwinger framework with those of lattice QCD and the available experimental data. The general aim is to identify the underlying physical mechanisms behind the plethora of observable phenomena in terms of the underlying quark and gluon degrees of freedom.

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Section: Verification Of the Discrepancymentioning

confidence: 99%

“…This is worked out in detail in Refs. [692,693]. For example, for a scattering amplitude with external pion legs one has to take the residue of the pseudoscalar vertex at the pion pole, which has the same effect as replacing the vertex Γ µ by the onshell pion amplitude.…”

Section: Verification Of the Discrepancymentioning

confidence: 99%

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

Self Cite

421

530

View full text Add to dashboard Cite

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“…Thus, our approach is applicable not only to 3γ decay, but also to other processes involving one, two, three, or more bosons "attached" to quark propagators, as for example, in descriptions of electromagnetic form factors [42], Compton scattering [28] and the closely related electromagnetic and pionic corrections [43,44], three-meson decay [45], meson-meson scattering [41,46], photon-photon scattering [37], etc. Some further examples of such matrix elements have been investigated in Ref.…”

Section: Discussionmentioning

confidence: 99%

“…The successfully developing continuum QCD approach [23][24][25][26][27][28][29], which is based on the DS equations of QCD, is a natural framework for further application of the results presented in this paper.…”

Section: Introductionmentioning

confidence: 99%

Gauge invariant formulation of3γdecay of particle-antiparticle bound states

2015

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We construct the gauge invariant three-photon decay amplitude of particle-antiparticle bound states modeled by the Dyson-Schwinger and Bethe-Salpeter equations. Application to the quarkantiquark (qq) bound states is emphasized. An essential aspect of our formulation is that it applies to any underlying quantum field theoretic model of the qq system, and not just to models, like exact QCD, where the quark self-energy Σ couples to the electromagnetic field solely via dressed quark propagators. In this way, applications to effective field theories and other QCD motivated models are envisioned. The three-photon decay amplitude is constructed by attaching currents to all possible places in the Feynman diagrams contributing to the dressed quark propagator. The gauge invariance of our construction is thus a direct consequence of respecting the underlying structure of the quantum field theory determining the dynamics. In the resultant expression for the three-photon decay amplitude, all the basic ingredients consisting of the bound state wave function, the final-state interaction qq t matrix, the dressed quark propagator, and dressed quark currents, are determined by a universal Bethe-Salpeter

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“…[12]. In a series of recent experiments at Jefferson Lab [16,17,18,19,20,21,22,23,24,25], the polarization transfer (PT) technique has been used to accurately determine the ratio G E /G M up to Q 2 = 8.5 GeV 2 . In addition, there have been complementary measurements using polarized targets at MIT-Bates [26] and Jefferson Lab [27].…”

Section: (Circles)mentioning

confidence: 99%