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In treating the relativistic three-quark problem, a dressed-quark propagator parameterization is used which is compatible with recent lattice data and pion observables. Furthermore two-quark correlations are modeled as a series of quark…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. Oettel , R. Alkofer

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 electromagnetic form factors of the nucleon are calculated at order $q^4$ in the relativistic formulation of baryon chiral perturbation theory. In order to obtain a consistent power counting for the renormalized diagrams we make use of…

Nuclear Theory · Physics 2009-11-10 Thomas Fuchs , Jambul Gegelia , Stefan Scherer

We determine the nucleon neutral weak electromagnetic form factors $G^{Z,p(n)}_{E,M}$ by combining results from light-front holographic QCD and lattice QCD calculations. We deduce nucleon electromagnetic form factors from light-front…

High Energy Physics - Phenomenology · Physics 2017-11-21 Raza Sabbir Sufian

In this work, we study the electric and magnetic Sachs form factors for proton and neutron by using a deformed gravity/gauge model. We describe holographically baryons as well as gauge bosons which are ruled by the parameters $k_{B}$ and…

High Energy Physics - Phenomenology · Physics 2021-09-23 Miguel Angel Martin Contreras , Eduardo Folco Capossoli , Danning Li , Alfredo Vega , Henrique Boschi-Filho

We present an alternative parameterization of the quark-diquark model of baryons which particularly takes care of the most recent proton electric form-factor data from the E136 experiment at SLAC. In addition to electromagnetic form factors…

High Energy Physics - Phenomenology · Physics 2009-10-22 R. Jakob , P. Kroll , M. Schuermann , W. Schweiger

We solve the nucleon's wave functions from the eigenstates of the light-front quantum chromodynamics Hamiltonian for the first time, using a fully relativistic and nonperturbative approach based on light-front quantization, without an…

High Energy Physics - Phenomenology · Physics 2024-08-22 Siqi Xu , Yiping Liu , Chandan Mondal , Jiangshan Lan , Xingbo Zhao , Yang Li , James P. Vary

We present analytic parametrizations for the $\gamma^\ast N \to N(1440)$ form factors derived from light-front holography in leading twist approximation. The new parametrizations describe the electromagnetic form factors using analytic…

High Energy Physics - Phenomenology · Physics 2017-09-25 G. Ramalho

The nucleon isovector electromagnetic form factors are calculated up to next-to-next-to-leading order by combining relativistic chiral perturbation theory (ChPT) of pion, nucleon, and $\Delta$(1232) with dispersion theory. We specifically…

High Energy Physics - Phenomenology · Physics 2023-12-18 Fernando Alvarado , Di An , Luis Alvarez-Ruso , Stefan Leupold

We quantify the importance of dynamical spin effects in the holographic light-front wavefunctions of the pion, kaon, $\eta$ and $\eta^\prime$. Using a universal AdS/QCD scale and constituent quark masses, we find that such effects are…

High Energy Physics - Phenomenology · Physics 2018-08-22 Mohammad Ahmady , Chandan Mondal , Ruben Sandapen

A workable basis of quark configurations $s^3$, $s^2p$ and $sp^2$ at light front has been constructed to describe the high-$Q^2$ behavior of transition form factors and helicity amplitudes in the electroproduction of the lightest nucleon…

High Energy Physics - Phenomenology · Physics 2019-11-20 Igor T. Obukhovsky , Amand Faessler , Dimitry K. Fedorov , Thomas Gutsche , Valery E. Lyubovitskij

A Poincar\'e-covariant quark+diquark Faddeev equation is used to compute nucleon elastic form factors on $0\leq Q^2\leq 18 \,m_N^2$ ($m_N$ is the nucleon mass) and elucidate their role as probes of emergent hadronic mass in the Standard…

Light-Front Quantization -- Dirac's "Front Form" -- provides a physical, frame-independent formalism for hadron dynamics and structure. Observables such as structure functions, transverse momentum distributions, and distribution amplitudes…

High Energy Physics - Phenomenology · Physics 2015-12-22 Stanley J. Brodsky

We present the experimental status of electromagnetic hadron form factors. New and surprising results, based on polarization measurements, have been recently obtained for the electric proton and neutron form factors. In particular, the…

High Energy Physics - Phenomenology · Physics 2015-06-25 Egle Tomasi-Gustafsson

We compute electroweak form factors of the nucleon and photon transition form factors of non-strange baryon resonances up to the third resonance region in a model with instanton-induced interaction. The calculation is based on the…

High Energy Physics - Phenomenology · Physics 2007-05-23 Dirk Merten , Ulrich Loering , Klaus Kretzschmar , Bernard Metsch , Herbert-R. Petry

In a model where constituent quarks and diquarks interact through quark exchange the Bethe-Salpeter equation in ladder approximation for the nucleon is solved. Quark and diquark confinement is effectively parametrized by choosing…

High Energy Physics - Phenomenology · Physics 2016-09-06 G. Hellstern. R. Alkofer , M. Oettel , H. Reinhardt

A remarkable feature of QCD is that the mass scale which controls color confinement and hadron mass scales does not appear explicitly in the QCD Lagrangian. However, de Alfaro, Fubini, and Furlan have shown that a mass scale can appear in…

High Energy Physics - Phenomenology · Physics 2016-11-23 Stanley J. Brodsky

We calculate the decay constants of light and heavy-light pseudoscalar and vector mesons with improved soft-wall holographic wavefuntions, which take into account the effects of both quark masses and dynamical spins. We find that the…

High Energy Physics - Phenomenology · Physics 2018-05-15 Qin Chang , Xiao-Nan Li , Xin-Qiang Li , Fang Su

We investigate the effect of different forms of relativistic spin coupling of constituent quarks in the nucleon electromagnetic form factors. The four-dimensional integrations in the two-loop Feynman diagram are reduced to the null-plane,…

Nuclear Theory · Physics 2014-11-18 W. R. B. de Araujo , E. F. Suisso , T. Frederico , M. Beyer , H. J. Weber

The nucleon is described as a bound state of a quark and an extended diquark. Hereby the notion ``diquark'' refers to the modelling of separable correlations in the two-quark Green's functions. Binding of quarks and diquarks takes place via…

High Energy Physics - Phenomenology · Physics 2017-08-23 R. Alkofer , M. Oettel