Coordinatori
Parallel 3: Advances in the modeling of baryon spectrum and structure
- Christian Fisher
Parallel 3: Partial wave analyses and baryon resonance parameter extraction
- Alfred Svarc (Rudjer Boskovic Institute)
Parallel 3: Hyperon production with electromagnetic probes
- Daniel Carman (Jefferson Laboratory)
Parallel 3: Polarization observables photo- and electro- production of mesons off nucleons
- William Briscoe (The George Washington University)
Parallel 3: Advances in the modeling of baryon spectrum and structure
- Christian Fischer
The last two decades have witnessed the discovery of a myriad of new and unexpected hadrons. Hadron spectroscopy provides direct physical measurements that shed light on the non-perturbative behavior of quantum chromodynamics (QCD) and the new pentaquark states observed by LHCb offer unique insights into the QCD dynamics in hadron structures. In this talk, some of the main experimental...
Hadron electromagnetic form factors describe the intrinsic dynamics of the charge and magnetic distributions in composite particles. They are experimentally accessible through (un)polarized cross sections measurements and angular distributions in the crossing symmetry related reactions : electron-hadron elastic scattering and electron-positron annihilation into hadron-antihadron (and its...
A very important contribution of dilepton production in pion-nucleon collisions comes from the Dalitz decay of s-channel baryon resonances, R->Ne+e-. These dileptons originate from a virtual photon with small timelike squared four-momentum q^2, therefore the study of this reaction gives access to the electromagnetic interaction of baryon resonances in a kinematical domain inaccessible...
We describe the application of a model-independent reconstruction method to experimental data in order to identify complex poles of overlapping resonances. The algorithm is based on the Schlessinger Point Method where data points are interpolated using a continued-fraction expression. Statistical uncertainties of the experimental data are propagated with resampling. In order to demonstrate the...
A rigorous identification of physical states from scattering experiments is possible by tracing the pole origin of the observed peaks. The identification becomes nontrivial if a peak appears very close to a two-hadron threshold. In this work we discuss how one can utilize a neural network to help map the observed peaks with the nature of S-matrix pole. Specifically, we can teach a deep neural...
The electric ($\alpha_{\text{E1}}$) and magnetic ($\beta_{\text{M1}}$) scalar polarizabilities describe the response of the nucleon to an applied electric or magnetic field. They are not only fundamental properties related to the internal structure and dynamics of the nucleon, but they are important also in other areas of physics, such as atomic structure.
The A2@MAMI Collaboration has...
Not long ago, we have developed and implemented a novel (Jülich-Bonn-Washington) model for pion electroproduction off the proton. Based on phenomenological (Jülich-Bonn) model, it incorporated constraints from the photoproduction and scattering data. Going to non-zero virtuality of the photon (Q^2>0) it allows now to address the abundant (O(10^5)) electroproduction data.
In this talk we...
The photo-induced reactions are complementary to hadron-induced reactions in the study of excited baryons.
In particular, GeV photon beam can provide information on highly excited hadrons.
In the LEPS experiment at SPring-8, hadron photoproduction reactions have been studied using linearly polarized photons from laser Compton scattering up to 2.9 GeV. The LEPS experiment measured production...
The GlueX experiment at Jefferson Lab studies the spectrum of hadrons in photoproduction on a LH2 target. Its almost hermetic detector configuration is optimized to measure both charged and neutral final state particles with good resolutions. This allows GlueX to measure a wide range of different reactions, including those with strangeness. In this talk we are going to present our ongoing...
Photoproduction of a neutral pion, omega, or eta meson on the proton has been experimentally studied in their neutral decay modes at the LEPS2 BGOegg experiment with incident photon energies ranging from 1.3 GeV to 2.4 GeV. Differential cross sections, photon beam asymmetries, and spin density matrix elements are measured with high statistics and a wide angular region by using a large...
Hadrons are strongly interacting systems whose dynamics is driven by complex intercommunication between quarks and gluons. The theory of strong interaction, Quantum ChromoDynamics (QCD) , is supposed to describe all particles, however, due to numerical complexity we are still far away from reaching this goal. In such a situation, experimental knowledge about existing resonances becomes...
Our research contributes to a larger experimental program that seeks to shed light on the evolving status of the proton spectrum. Determining the hadronic spectrum is a complicated task due to the high number of excited states of the nucleon, all of which have large widths causing resonances to overlap. Also, these resonances may decay into a multitude of decay channels.
In this talk, we...
The FROST experiment at Jefferson Lab used the CLAS detector in Hall B with the intention of performing a complete and over-determined measurement of the polarisation observables associated with strangeness photoproduction, in combination with data from previous JLab experiments as part of the N* program. This was achieved by utilising the FROST polarised target in conjunction with polarised...
We shall present a recent calculation of \gamma^{(*)}p->N(1535) transition form factors, based upon a continuum Schwinger method approach which employs a Poincaré-covariant Faddeev equation to describe baryons as composite states. Although limited to a symmetry-preserving contact interaction model of QCD, the results herein shown serve as benchmarks for future more sophisticated calculations;...
Hadrons are strongly interacting particles composed of quarks and gluons and described by Quantum Chromodynamics (QCD). Their internal structure can be described in terms of structure functions that encode, for example, the momentum and spin distributions of their constituents. Parton distribution functions (PDFs), for example, describe the quark and gluon momentum distributions inside a...
