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The structure of the nucleon and the first radial excitation of the nucleon, the Roper, $N(1440)$, is studied within the formalism of Light-Front holography. The nucleon elastic form factors and $\gamma^\ast N \to N(1440)$ transition form…

High Energy Physics - Phenomenology · Physics 2018-03-07 G. Ramalho , D. Melnikov

We explore the meson cloud contribution to nucleon electromagnetic form factors in dispersion relation approach. In our calculations, experimental data on transition amplitudes for pion-nucleon scatterings are taken directly as inputs, with…

High Energy Physics - Phenomenology · Physics 2024-09-27 Ek-ong Atthaphan , Attaphon Kaewsnod , Kai Xu , Moh Moh Aung , Warintorn Sreethawong , Ayut Limphirat , Yupeng Yan

The covariant spectator quark model is applied to the $\gamma^\ast N \to N^\ast(1520)$ reaction. The valence quark contributions to the electromagnetic form factors and helicity transition amplitudes are estimated from the covariant…

High Energy Physics - Phenomenology · Physics 2014-05-28 G. Ramalho , M. T. Peña

The meson-cloud model of the nucleon consisting of a system of three valence quarks surrounded by a meson cloud is applied to study the electroweak structure of the proton and neutron. The electroweak nucleon form factors are calculated…

High Energy Physics - Phenomenology · Physics 2015-05-13 B. Pasquini , S. Boffi

We study the electromagnetic structure of the nucleon within a hybrid constituent-quark model that comprises, in addition to the $3q$ valence component, also a $3q$+$\pi$ non-valence component. To this aim we employ a Poincar\'e-invariant…

High Energy Physics - Phenomenology · Physics 2016-04-20 Daniel Kupelwieser , Wolfgang Schweiger

The axial-vector form factor of the nucleons is considered in the framework of hard-wall model of holographic QCD. A new interaction term between the bulk gauge and matter fields was included into the interaction Lagrangian. We obtain the…

High Energy Physics - Theory · Physics 2017-05-04 Shahin Mamedov , Berin Belma Sirvanli , Ibrahim Atayev , Narmin Huseynova

The long-distance structure of the interacting nucleon receives important contributions from its couplings to light hadronic degrees of freedom -- a light meson cloud -- while an analogous nonperturbative mechanism is expected to generate…

High Energy Physics - Phenomenology · Physics 2015-06-02 T. J. Hobbs

We compute the nucleon axial and induced pseudoscalar form factors using three ensembles of gauge configurations, generated with dynamical light quarks with mass tuned to approximately their physical value. One of the ensembles also…

Precise knowledge of the nucleon's axial-current form factors is crucial for modeling GeV-scale neutrino-nucleus interactions. Unfortunately, the axial form factor remains insufficiently constrained to meet the precision requirements of…

Nuclear Theory · Physics 2020-11-04 Xilin Zhang , T. J. Hobbs , Gerald A. Miller

The axial form factor of the nucleon is studied in a two-component model consisting of a three-quark intrinsic structure surrounded by a meson cloud. The experimental data in the space-like region are well reproduced with a minimal number…

Nuclear Theory · Physics 2008-11-26 C. Adamuščín , E. Tomasi-Gustafsson , E. Santopinto , R. Bijker

A joint fit to neutrino-nucleon scattering and pion electroproduction data is performed to evaluate the nucleon axial form factor in the two-component model consisting of a three-quark intrinsic structure surrounded by a meson cloud.…

High Energy Physics - Phenomenology · Physics 2021-04-28 G. D. Megias , S. Bolognesi , M. B. Barbaro , E. Tomasi-Gustafsson

The meson-cloud model of the nucleon consisting of a system of three valence quarks surrounded by a meson cloud is applied to study the electroweak structure of the proton and neutron. Light-cone wavefunctions are derived for the dressed…

High Energy Physics - Phenomenology · Physics 2008-11-26 B. Pasquini , S. Boffi

The vector dominance of the electromagnetic form factors both for mesons and baryons arises naturally in holographic QCD, where both the number of colors and the 't Hooft coupling are taken to be very large, offering a bona-fide derivation…

High Energy Physics - Phenomenology · Physics 2008-11-26 Deog Ki Hong , Mannque Rho , Ho-Ung Yee , Piljin Yi

The nucleon axial form factor is a dominant contribution to errors in neutrino oscillation studies. Lattice QCD calculations can help control theory errors by providing first-principles information on nucleon form factors. In these…

High Energy Physics - Lattice · Physics 2016-10-17 Aaron S. Meyer , Richard J. Hill , Andreas S. Kronfeld , Ruizi Li , James N. Simone

We discuss how to calculate form factors using a holographic model of QCD, mainly focusing on vector, axial, and pseudoscalar mesons. We illustrate the techniques on gravitational form factors (which are useful for constraining the…

High Energy Physics - Phenomenology · Physics 2009-11-13 Carl E. Carlson

The unpolarized, helicity and transversity parton distribution functions of the nucleon are studied within a convolution model where the bare nucleon is dressed by its virtual meson cloud. Using light-front time-ordered perturbation theory,…

High Energy Physics - Phenomenology · Physics 2017-05-31 S. Kofler , B. Pasquini

Flagship neutrino oscillation experiments depend on precise and accurate theoretical knowledge of neutrino-nucleon cross sections across a variety of energies and interaction mechanisms. Key ingredients to the amplitudes that make up these…

High Energy Physics - Lattice · Physics 2026-01-07 Aaron S. Meyer

Despite the prominence of tensor mesons in photon-photon collisions, until recently their contribution to the hadronic light-by-light (HLbL) scattering part of the anomalous magnetic moment of the muon has been estimated to be at the level…

High Energy Physics - Phenomenology · Physics 2025-06-03 Luigi Cappiello , Josef Leutgeb , Jonas Mager , Anton Rebhan

Holographic models of QCD provide the spectrum of heavy vector meson masses and electromagnetic decay constants through bulk computations of the current-current correlation function. Conversely, the phenomenology of heavy vector mesons is…

High Energy Physics - Phenomenology · Physics 2025-09-12 Saulo Diles , Miguel Angel Martin Contreras , Alfredo Vega

We study the influence of non-valence quark-pair contributions in weak transition form factors of heavy-light mesons. Form factors are first calculated for spacelike momentum transfers in a reference frame where such contributions are…

High Energy Physics - Phenomenology · Physics 2022-02-10 María Gómez-Rocha , Oliver Heger , Wolfgang Schweiger
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