Photon– and pion–nucleon interactions in a unitary and causal effective field theory based on the chiral Lagrangian

Gasparyan, A. M.; Lutz, Matthias

doi:10.1016/j.nuclphysa.2010.08.006

Cited by 119 publications

(166 citation statements)

References 89 publications

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“…Among those are the Sato-Lee model [70], which has been extended by the EBAC [71][72][73] and ANL/Osaka collaborations [74] and extensively applied to analyze pion photo-and electroproduction data. The Dubna-Mainz-Taiwan (DMT) [75,76], Valencia [77], Jülich-Bonn [78,79] and GSI models [80][81][82] have been developed along similar lines. Theoretical constraints like unitarity and analyticity of the S-matrix are manifest in these approaches.…”

Section: Helicity Amplitudes Vs Transition Form Factorsmentioning

confidence: 99%

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

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: Helicity Amplitudes Vs Transition Form Factorsmentioning

confidence: 99%

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

421

530

View full text Add to dashboard Cite

show abstract

“…From the theory side, in order to describe such a fundamental process, dispersion relations for πN scattering have been investigated several decades ago [3][4][5] and many phenomenological models and different approaches have been proposed (see, e.g., refs. [6][7][8][9][10][11][12][13]). Roy-Steiner equations for the pion-nucleon scattering have been also analysed recently [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Pion-nucleon scattering in covariant baryon chiral perturbation theory with explicit Delta resonances

Yao

Siemens

Bernard

et al. 2016

J. High Energ. Phys.

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We present the results of a third order calculation of the pion-nucleon scattering amplitude in a chiral effective field theory with pions, nucleons and delta resonances as explicit degrees of freedom. We work in a manifestly Lorentz invariant formulation of baryon chiral perturbation theory using dimensional regularization and the extended on-mass-shell renormalization scheme. In the delta resonance sector, the on mass-shell renormalization is realized as a complex-mass scheme. By fitting the low-energy constants of the effective Lagrangian to the S-and P -partial waves a satisfactory description of the phase shifts from the analysis of the Roy-Steiner equations is obtained. We predict the phase shifts for the D and F waves and compare them with the results of the analysis of the George Washington University group. The threshold parameters are calculated both in the delta-less and delta-full cases. Based on the determined low-energy constants, we discuss the pion-nucleon sigma term. Additionally, in order to determine the strangeness content of the nucleon, we calculate the octet baryon masses in the presence of decuplet resonances up to next-to-next-to-leading order in SU(3) baryon chiral perturbation theory. The octet baryon sigma terms are predicted as a byproduct of this calculation.

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“…The purpose of this contribution is to apply a recently proposed unitarization scheme [4] to Goldstone boson scattering based on the chiral Lagrangian supplemented with light vector mesons. There are several reasons for considering the light vector mesons as explicit degrees of freedom.…”

Section: Introductionmentioning

confidence: 99%

Chiral dynamics with vector fields: an application toππandπKscattering

Danilkin

Lutz

2012

EPJ Web of Conferences

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Abstract.A theoretical study of Goldstone boson scattering based on the chiral Lagrangian with vector meson fields is presented. In application of a recently developed novel approach we extrapolate subthreshold partial-wave amplitudes into the physical region. The constraints set by micro-causality and coupled-channel unitarity are kept rigourously. It is shown that already the leading order subthreshold amplitudes lead to s-and p-wave ππ and πK phase shifts are in agreement with the experimental data up to about 1.2 GeV.

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Photon– and pion–nucleon interactions in a unitary and causal effective field theory based on the chiral Lagrangian

Cited by 119 publications

References 89 publications

Baryons as relativistic three-quark bound states

Baryons as relativistic three-quark bound states

Pion-nucleon scattering in covariant baryon chiral perturbation theory with explicit Delta resonances

Chiral dynamics with vector fields: an application toππandπKscattering

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