Helicity amplitudes and electromagnetic decays of hyperon resonances

Cauteren, T. Van; Ryckebusch, Jan; Metsch, B.; Petry, Herbert R.

doi:10.1140/epja/i2005-10190-3

Cited by 38 publications

(38 citation statements)

References 46 publications

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“…The validity of such models for non-vanishing momentum transfer is questionable and more sophisticated quark models have been developed. For example, a reduction of the Bethe-Salpeter equation by using instantaneous interactions was used in [628,629] to study electromagnetic form factors of octet hyperon resonances. A reduction to a quark-diquark system has been used in [507] within an NJL model for the interactions and in the covariant spectator formalism in [630].…”

Section: Hyperon Form Factorsmentioning

confidence: 99%

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

417

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: Hyperon Form Factorsmentioning

confidence: 99%

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

417

530

View full text Add to dashboard Cite

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“…The mass spectrum of negative-parity nucleon resonances starts with the well known spin doublet N (1535)S 11 , N (1520)D 13 in the second, and the spin triplet N (1650)S 11 , N (1700)D 13 , N (1675)D 15 in the third resonance region. Within SU(6), these states belong to a 70-plet.…”

Section: Negative Parity Nucleon Resonancesmentioning

confidence: 99%

“…The effective one-gluon exchange interaction [1,2,3,4] was replaced by one-boson exchange interactions between constituent quarks [6] or by instanton-induced interactions [5]. The improved baryon wave functions provided the basis for calculations of partial decay widths [7,8,9,10,11], of helicity amplitudes [12,13], and of form factors [14,15,16,17]. The spectrum of nucleon and ∆ resonances calculated on the lattice [18] shows striking agreement with expectations based on quark models: with increasing mass, there are alternating clusters of states with positive and with negative parity.…”

Section: Introductionmentioning

confidence: 99%

Nucleon resonances in the fourth-resonance region

et al. 2011

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Abstract.Nucleon and ∆ resonances in the fourth resonance region are studied in a multichannel partial-wave analysis which includes nearly all available data on pion-and photo-induced reactions off protons. In the high-mass range, above 1850 MeV, several alternative solutions yield a good description of the data. For these solutions, masses, widths, pole residues and photo-couplings are given. In particular, we find evidence for nucleon resonances with spin-paritiesFor one set of solutions, there are four resonances forming naturally a spin-quartet of resonances with orbital angular momentum L = 2 and spin S = 3/2 coupling to J = 1/2, · · · , 7/2. Just below 1.9 GeV we find a spin doublet of resonances with J P = 1/2 − and 3/2 − . Since a spin partner with J P = 5/2 − is missing at this mass, the two resonances form a spin doublet which must have a symmetric orbital-angular-momentum wave function with L = 1. For another set of solutions, the four positive-parity resonances are accompanied by mass-degenerate negativeparity partners -as suggested by the conjecture of chiral symmetry restoration. The possibility of a J P = 1/2 + , 3/2 + spin doublet at 1900 MeV belonging to a 20-plet is discussed.

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“…Several authors have studied the decay properties of the Λ(1405) within constituent quark models [15][16][17][18][19][20]. However, the calculated strong decay width of the Λ(1405) in the traditional constituent quark model turns out to be much smaller than the value Γ = 50 ± 2 MeV reported by the Particle Data Group (PDG) [37].…”

Section: Introductionmentioning

confidence: 96%