Octet baryon electromagnetic form factors in a relativistic quark model

Ramalho, G.; Tsushima, K.

doi:10.1103/physrevd.84.054014

Cited by 42 publications

(81 citation statements)

References 124 publications

(357 reference statements)

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“…The meson cloud contribution to the nucleon wave function is estimated to be of the order of a few percent [25][26][27][28]. As for the Roper, the meson cloud seems to play a more prominent role.…”

Section: Introductionmentioning

confidence: 99%

Valence quark contributions for the γ*N→N(1440) form factors from light-front holography

Ramalho

Melnikov

2018

Phys. Rev. D

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The structure of the nucleon and the first radial excitation of the nucleon, the Roper, Nð1440Þ, is studied within the formalism of light-front holography. The nucleon elastic form factors and γ Ã N → Nð1440Þ transition form factors are calculated under the assumption of the dominance of the valence quark degrees of freedom. Contrary to the previous studies, the bare parameters of the model associated with the valence quark are fixed by the empirical data for large momentum transfer (Q 2 ) assuming that the corrections to the three-quark picture (meson cloud contributions) are suppressed. The γ Ã N → Nð1440Þ transition form factors are then calculated without any adjustable parameters. Our estimates are compared with results from models based on valence quarks and others. The model compares well with the γ Ã N → Nð1440Þ transition form factor data, suggesting that meson cloud effects are not large, except in the region Q 2 < 1.5 GeV 2 . In particular, the meson cloud contributions for the Pauli form factor are small.

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Section: Introductionmentioning

confidence: 99%

Valence quark contributions for the γ*N→N(1440) form factors from light-front holography

Ramalho

Melnikov

2018

Phys. Rev. D

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“…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]. In the latter the emphasis was placed on studying the role of pion cloud effects in form factors.…”

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

418

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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“…(4.1), has a small magnitude in the lattice QCD simulations for pion masses around 0.23 GeV. Notice also that the term under discussion is negative because G MC A has a faster falloff than G [25,57,58,60,74,76].…”

Section: B Using Lattice Qcd Informationmentioning

confidence: 99%

“…More details about the extension of the spectator model to the lattice QCD regime can be found in Refs. [25,[72][73][74][75][76].…”

Section: Information From Lattice Qcdmentioning

confidence: 99%

“…The question of whether the light-front meson cloud contribution is important or not is pertinent, because in principle the corrections associated with the meson cloud should be expressed in terms of parameters related to the microscopic structure, such as meson-baryon couplings and the photon-meson couplings [23][24][25]. As discussed later, in the case of a holographic model, the estimates of the transition form factors depend only on the couplings associated with quarks without explicit reference to the substructure associated with the meson cloud.…”

Section: Introductionmentioning

confidence: 99%

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Holographic estimate of the meson cloud contribution to nucleon axial form factor

Ramalho

2018

Phys. Rev. D

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We use light-front holography to estimate the valence quark and the meson cloud contributions to the nucleon axial form factor. The free couplings of the holographic model are determined by the empirical data and by the information extracted from lattice QCD. The holographic model provides a good description of the empirical data when we consider a meson cloud mixture of about 30% in the physical nucleon state. The estimate of the valence quark contribution to the nucleon axial form factor compares well with the lattice QCD data for small pion masses. Our estimate of the meson cloud contribution to the nucleon axial form factor has a slower falloff with the square momentum transfer compared to typical estimates from quark models with meson cloud dressing.

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Octet baryon electromagnetic form factors in a relativistic quark model

Cited by 42 publications

References 124 publications

Valence quark contributions for the γ*N→N(1440) form factors from light-front holography

Valence quark contributions for the γ*N→N(1440) form factors from light-front holography

Baryons as relativistic three-quark bound states

Holographic estimate of the meson cloud contribution to nucleon axial form factor

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