Bulletin of the American Physical Society
2020 Fall Meeting of the APS Division of Nuclear Physics
Volume 65, Number 12
Thursday–Sunday, October 29–November 1 2020; Time Zone: Central Time, USA
Session FQ: Mini-Symposium: Electromagnetic FF of N*'s III |
Hide Abstracts |
Chair: Victor Mokeev, Jefferson Lab |
Friday, October 30, 2020 2:00PM - 2:12PM |
FQ.00001: Exploring the Emergence of Deformation Dominance in Nuclear Structure from Strong QCD Jerry Draayer, David Kekejian, Kristina Launey, Viktor Mokeev, Craig Roberts The dominance of deformation across the chart of the nuclides is traced back to a (non-compact) symmetry of a generalized three-dimensional harmonic oscillator structure that emerges directly from quantum field theory considerations. This suggests one should look more deeply into the structure of nucleons to see, first if they are deformed, and if so how that deformation arises from the quark-gluon substructure of nucleons (and other hadrons) and how it is emerges in realistic nucleon-nucleon interactions. The goal is to probe more deeply into the ab initio features that lead to a major simplicity, where deformation dominates, found within the complexity of nuclear structure. Analyses of the experimental results on pion and nucleon elastic as well as N ---> N* transition form factors within a continuum QCD framework will facilitate this effort. [Preview Abstract] |
Friday, October 30, 2020 2:12PM - 2:24PM |
FQ.00002: N$\to $N* transition GPD measurements with CLAS12 at JLAB Stefan Diehl The measurement of transition GPDs is a unique tool to understand the 3 dimensional structure and the mechanical properties of nucleon resonances for the first time. To extract transition GPDs, the non-diagonal DVCS process can be used. In this process a pion-nucleon system, originating from the decay of an N* resonance, is produced in addition to a real photon. Because the factorisation of this process amplitude requires the constraints on Mandelstam variable t and photon virtuality Q$^{\mathrm{2}}$ (-t/Q$^{\mathrm{2}}$ \textless \textless 1) and several final state particles have to be detected for a clean identification, CLAS12 in combination with the upgraded CEBAF accelerator at JLAB provides a unique opportunity to study this process. The talk will introduce the topic and present an on-going analysis effort on the recently collected CLAS12 data. The analysis will be discussed in the context of theoretical predictions for the $p \to \Delta $ transition GPDs. [Preview Abstract] |
Friday, October 30, 2020 2:24PM - 2:36PM |
FQ.00003: Nucleon resonance spectrum from Regge systematic César Fernández Ramírez, Jorge Antonio Silva-Castro, Miguel Albaladejo, Igor Danilkin, Andrew Jackura, Vincent Mathieu, Jannes Nys, Alessandro Pilloni, Adam Szczepaniak, Geoffrey Fox We use Regge phenomenology to study the structure of the poles of the N* and Delta* spectrum. We employ the available pole extractions from partial wave analysis of meson scattering and photo- production data. We assess the importance of the imaginary part of the poles (widths) to obtain a consistent determination of the parameters of the Regge trajectory. We compare the several pole extractions and show how Regge phenomenology can be used to gain insight into the internal structure of baryons. We find that the majority of the states in the parent Regge trajectories are compatible with a mostly compact three- quark state picture. [Preview Abstract] |
Friday, October 30, 2020 2:36PM - 2:48PM |
FQ.00004: Single Pion Electroproduction with CLAS in the $Q^{2}$ Region of $1.0-2.0 \,\mathrm{GeV}^{2}$ Nicholas Tyler The results on nucleon resonance electroexcitation amplitudes give unique insight into the dynamics of the strong interaction. They elucidate the structure of the nucleon and its excitations, and in total better our understanding of quantum chromodynamics. Preliminary results from an ongoing study of single pion electroproduction from the CLAS experimental runs will be shown. In particular the cross sections from the resonance region produced from low photon virtualities, $Q^2$. Currently there is a gap in the single pion cross section data of $Q^{2}$ between $1.0-2.0 \,\mathrm{GeV}^{2}$. Studies of the N$\pi$ channel in this region will add to our understanding and be a valuable input to theoretical reaction models. [Preview Abstract] |
Friday, October 30, 2020 2:48PM - 3:00PM |
FQ.00005: Beam asymmetry for exclusive $\pi $0p, $\pi +$n electroproduction in the resonance region with the CLAS12 Valerii Klimenko, Viktor Mokeev The N* program with the CLAS12 detector offers a unique opportunity to explore the nucleon resonance structure at highest photon virtualities ever achieved, in the range of Q\textasciicircum 2\textgreater 5.0 GeV\textasciicircum 2. Studies of resonance electroexcitation in Npi~ electroproduction represent the important part in these efforts. \newline The~ preliminary CLAS12 results on beam spin asymmetry in pi\textasciicircum 0p and pi\textasciicircum $+$n exclusive channels will be presented~ in the talk. The data were collected with the electron beam energy 10.6 GeV in the resonance region of W\textless 2.0 GeV and in the range of photon virtualities 1.0 \textless Q\textasciicircum 2\textless 10.0 GeV\textasciicircum 2. Combined studies of beam asymmetries and Npi exclusive cross sections are critical in order to obtain the first results on electrocouplings of all prominent in these channels resonances at Q\textasciicircum 2\textgreater 5.0 GeV\textasciicircum 2. [Preview Abstract] |
Friday, October 30, 2020 3:00PM - 3:12PM |
FQ.00006: CLAS12 Charged Two-Pion Electroproduction Off the Proton Krishna Neupane The study of the structure of excited states of the nucleon is one of the major fields to investigate the strong interaction dynamics that underlie baryon generation from quarks and gluons. CLAS in Hall B at Jefferson Lab has already produced the dominant part of the available world data on charged double-pion electroproduction in the nucleon resonance region for photon virtualities, Q$^2$, up to 5 GeV$^2$. These data have allowed us to obtain the resonance electroexcitation amplitudes for most excited states in the mass range up to 1.8 GeV. This talk will highlight some recent CLAS results in this channel and focus particularly on preliminary results of one of the first measurements with the CLAS12 detector. CLAS12 is the only available facility in the world capable of exploring resonance electroexcitation amplitudes in the still almost uncharted range of Q$^2 >$ 5.0 GeV$^2$. The charged double-pion channel, offers a unique opportunity to explore the evolution of the resonance structure at the distances where the transition from quark-gluon confinement to pQCD regime is expected. [Preview Abstract] |
Friday, October 30, 2020 3:12PM - 3:24PM |
FQ.00007: Exclusive $\phi$ Meson Electroproduction with CLAS12 Brandon Clary The Continuous Electron Accelerator Facility Large Angle Spectrometer detector (CLAS12) at Jefferson Lab in Virginia has recently completed a successful period of data acquisition of a longitudinally polarized 10.6 GeV electron beam on a 5 cm unpolarized liquid hydrogen target. A program to study exclusive $\phi$ meson electroproduction is now underway as this is an ideal channel for quantifying the gluonic properties of the nucleon. This analysis focuses on the exclusive reaction $e p \to epK^+K^-$. The analysis strategy consists of two steps: first to establish the approach to the small-size regime by testing model-independent features of the reaction mechanism, such as the $Q^2$-independence of the t-slopes; then in a second step, extracting the gluonic size in the valence region as a function of $x_{B}$. This contribution will present a study to extract the beam spin asymmetry for this reaction. Ultimately, the asymmetry will shed light on the structure functions of the interference terms from the longitudinal and transverse cross section. [Preview Abstract] |
Friday, October 30, 2020 3:24PM - 3:36PM |
FQ.00008: Light front holography in exploration of the ground and excited nucleons Alexandre Deur Light front holography has emerged as a fruitful approach to describe the non-perturbative structure of hadrons. In this talk, I will discuss results from the bottom-up soft-wall AdS/CFT model developed by Brodsky, de Téramond and collaborators. After briefly describing the model, I will show how it successfully predicts the hadronic mass spectrum using $\Lambda_{QCD}$ as its only parameter. Then, I will show how the approach also predicts with a minimal number of parameters the nucleon form-factors, the polarized and unpolarized PDFs and the GPDs. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700