Conveners
3-dimensional structure of nucleon: GPD and FF: 02
- Paweł Sznajder (National Centre for Nuclear Research, Poland)
3-dimensional structure of nucleon: GPD and FF
- Paweł Sznajder (National Centre for Nuclear Research, Poland)
Description
Conveners: Barbara Pasquini, Sznajder Pawel, Stefan Diehl
At BESIII, the electromagnetic form factors (EMFFs) and the pair production cross sections of various baryons have been studied. The proton EMFF ratio |GE/GM| is determined precisely and line-shape of |GE| is obtained for the first time. The recent results of neutron EMFFs at BESIII show great improvement comparing with previous experiments. Cross sections of various baryon pairs (Lambda,...
The form factors are important physical quantities that characterize
the internal structure of a nucleon. In the classical picture, it
corresponds to the Fourier transform of the nucleon's three-dimensional
density distribution. Among them, the electromagnetic form factors are
the most well-known, with thousands of high-precision experimental data
accumulated to date. The axial form...
We present the first systematic study of the relativistic intrinsic spin structure of a general spin-$1/2$ hadron in position space. We show in particular that the slope of the nucleon axial form factor $G_A^Z(Q^2)$ in the forward limit, conventionally denoted as $R^2_A \equiv -\frac{6}{G_A^Z(0) } \frac{ \text{d} G_A^Z(Q^2) }{\text{d} Q^2} \Big|_{Q^2=0} $ in the literature, does not faithfully...
We present lattice QCD computations addressing crucial aspects of meson internal structure through electromagnetic form factors (EMFFs) and generalized parton distributions (GPDs). Utilizing physical masses and fine lattices, we calculate pion and kaon EMFFs at momentum transfers up to approximately 10 and 28 GeV$^2$, respectively, achieving good agreement with available experimental data at...
We present the first calculation of quantum electrodynamics (QED) nuclear medium effects under the experimental conditions of future Electron-Ion Collider (EIC) experiments. While prior studies have predominantly focused on elastic scattering, our investigation extends to the more complex scenarios of inelastic processes within a nuclear medium. For lead nuclei, our findings suggest that the...
We report recent advancements in understanding nucleon structure within the Basis Light-Front Quantization (BLFQ) framework—a fully relativistic, nonperturbative approach to solving quantum field theories. Starting with the leading Fock sector $|qqq\rangle$ and an effective light-front Hamiltonian incorporating confinement and one-gluon exchange, BLFQ has successfully described key nucleon...
We present a lattice QCD calculation for the leading-twist Light-cone Distribution Amplitudes (LCDAs) of the Lambda and Proton, within the framework of Large-momentum Effective Theory (LaMET). The numerical computation employs CLQCD ensembles with stout smeared clover fermions and a Symanzik gauge action. In order to obtain reliable results in both perturbative and non-perturbative regions, we...
Deeply Virtual Compton Scattering (DVCS) and exclusive $\pi^0$ electroproduction provide experimental access to Generalized Parton Distributions (GPDs). In these channels, the measured cross sections are expressed in terms of Compton Form Factors (CFFs), which correspond to the first moments of the underlying GPDs. From September 2023 to May 2024, Jefferson Lab Hall C conducted experiment...
The contribution of parton orbital motion to the nucleon spin structure is encoded in transverse-momentum dependent distributions (TMDs) and generalized parton distributions (GPDs). These distributions are primarily accessed through lepton-induced processes such as semi-inclusive deep-inelastic scattering (SIDIS) and Deeply Virtual Compton Scattering (DVCS). As a complementary approach,...
We present a comparative study of Compton Form Factor (CFF) extraction using pseudodata derived from Deeply Virtual Compton Scattering (DVCS) experiments at Jefferson Lab. The analysis is based on the twist-two formalism of Belitsky, Kirchner, and Müller, incorporating a minimally biased fitting strategy inspired by local fits to reduce model dependence. Two machine learning approaches are...
Deeply virtual Compton scattering (DVCS) is established as the golden channel for accessing generalized parton distributions (GPDs), which encode the nucleon's three-dimensional structure and are crucial for understanding the origin of nucleon spin. In this talk, I will summarize recent theoretical advances in predicting the DVCS process to higher perturbative orders. These developments are...
Exclusive heavy vector meson production is investigated in ep pp and pPb collisions employing GPD approach with GK model. Three sets gluon density are used to calculate exclusive heavy vetor meson production. The survival factors and equivalent photon approximation are applied to predict the exclusive heavy vector mesons photoproduction in proton-proton collisions. The GPD method prediction...
The structures related to shear and shear viscosity may appear in the expansion of energy-momentum tensor (EMT) in various processes.Such terms in various channels may be related either to naive T-oddness (like for Single Spin Asymmetries) or exotic quantum numbers. Their presence is constrained by the equivalebnce principle (EP) which holds exactly (in the forward limit) in the case of...
The energy-momentum tensor encodes the internal energy, spin, and stress distributions within hadrons, shedding new light on hadron structures and fundamental QCD problems such as confinement and the origin of hadron mass. In recent years, it has become possible to measure this quantity directly from experiments via generalized parton distributions, leading to growing interest in both...
The generalized distribution amplitudes (GDAs) have attracted attention in recent years because of their relation with the energy momentum tensor (EMT) form factors (FFs). The GDAs can be experimentally accessed through the study of amplitudes in $\gamma^{\ast} \gamma \to M_1 M_2$ and $\gamma^{\ast} \to M_1 M_2 \gamma$, where $M_1M_2$ is a pseudoscalar meson pair such as $\pi \eta $ and...
This presentation offers a unified set of results for the elastic electromagnetic and gravitational form factors of the pion, kaon, and nucleon, using continuum Schwinger function methods. A key feature of the study is the consistent treatment of dressed graviton–quark interactions, allowing seamless analysis across mesons and baryons. We find that the mass radii of pions and kaons are smaller...
Baryon-antibaryon generalized distribution amplitudes (GDAs) give an access to timelike gravitational form factors (GFFs) which are complementary to the spacelike ones which can be deduced from the hadronic generalized parton distributions (GPDs) measured in deep exclusive electroproduction processes. They allow to probe the GFFs of unstable baryons in the baryon octet, since the second...
