Conveners
Low Energy Spin Physics with Lepton, Photon and Hadron Probes: Low Energy I
- Annika Thiel (HISKP, Uni Bonn)
- Annika Thiel (HISKP Bonn)
Low Energy Spin Physics with Lepton, Photon and Hadron Probes: Low Energy II
- Thomas Jude (The University of Bonn)
Low Energy Spin Physics with Lepton, Photon and Hadron Probes: Low Energy III
- Chao Peng (Argonne National Laboratory)
Low Energy Spin Physics with Lepton, Photon and Hadron Probes: Low Energy IV
- Alexandre Deur (Thomas Jefferson National Accelerator Facility)
Low Energy Spin Physics with Lepton, Photon and Hadron Probes: Low Energy VI
- Michaela Thiel
We calculate the beam normal single-spin asymmetry $B_n$ in electron--proton elastic scattering from two-photon exchange amplitudes with resonance intermediate states of spin-parity $1/2^\pm$ and $3/2^\pm$ and mass $W < 1.8$ GeV. The latest CLAS exclusive meson electroproduction data are used as input for the transition amplitudes from the proton to the excited resonance states. The spin 3/2...
Pushing the precision frontiers further in nuclear physics brings up new experimental challenges as well as the demand for more sophisticated theoretical calculations. Especially in parity- violation electron scattering experiments, the contribution from higher order processes, such as two-photon exchange, is comparable in size with the observed asymmetry $A_{PV}$. Hence, a precise knowledge...
Normal spin asymmetries are an important tool in the study of hadron structure. They can be studied in a wide range of reactions in electron scattering, namely elastic, inclusive, semi-inclusive, and a wide range of energies. Experimental results are still few and far apart. Theoretical means of study are still limited, with the low energy purely elastic case being the only one under almost...
A polarized target program is being developed for GlueX in Hall D at Jefferson Lab. Consisting of a high intensity tagged photon beam with energies up to 12 GeV, a hermetic solenoidal spectrometer sensitive to charged and neutral particles and a demonstrated DAQ rate of 80 kHz, the apparatus is ideal for many polarized target experiments with longitudinal target polarization. Already...
The Gerasimov-Drell-Hearn (GDH) sum rule shows a fundamental relation between real photon absorption and the anomalous magnetic moment to the spin structure of the target. The generalized form of GDH sum rule extends this relation to finite four-momentum transfer squared (Q$^2 > 0$). Jefferson Lab (JLab) experiment E97-110 was carried out with a longitudinally polarized electron beam and...
The ultracold neutron (UCN) source at the Paul Scherrer Institut is being successfully operated since 2011 and has provided UCN for example to the nEDM experiment, which has placed the tightest constraints to date on the neutron's electric dipole moment in 2020. Currently the successor experiment n2EDM is being commissioned at the same position. At the second beam port, the neutron lifetime...
Investigating the baryon excitation spectrum is essential for understanding the internal dynamics of baryons and quantum chromodynamics (QCD) in the non-perturbative regime. Experimentally, the baryon spectrum can be probed with a real photon beam in photoproduction reactions. Partial wave analyses are performed to extract the baryon resonance parameters from the experimental data. For an...
Generalized parton distributions (GPDs) are important quantities that characterize the 3-D structure of hadrons, and complement the information extracted from TMDs. They provide information about the partons’ momentum distribution and also on their distribution in position space. Most of the information from lattice QCD is on the Mellin moments of GPDs, namely form factors and their...
{\bf Abstract}
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Recently CERN has discovered three new exotic particles in LHCb. The particle are $T_{cso}$ $(2900)^{++}$, a doubly charged tetraquark with quark configuration (csu$\overline{d}$), $T_{cso}$ $(2900)^{0}$, a neutral tetraquark with quark configuration (cds$\overline{u}$) and a neutral pentaquark $P_{\psi s}$ $(4338)^{0}$ with quark configuration (c$\overline{c}$...
An upcoming experiment at the High Intensity Game Source (HIGS) at the Triangle Universities Nuclear Laboratory (TUNL) will measure the polarization of recoiling neutrons from the photodisintegration of deuterium nuclei. As the simplest, multi-body nucleus, the deuteron offers a unique opportunity to study nucleon-nucleon interactions. Over the years, nuclear theory has developed to be able to...
I will discuss the importance of the T20 quantity and the basic experimental setup for a measurement of d (γ, n). Multiple measurements have suggested the existence of a channel around 9 MeV above the two nucleon masses in the center of mass frame. This diverges from calculations from current nuclear theory, and this experiment will focus on this new channel and yield information on the nature...
A central problem of modern physics research is the solution to QCD in the non-perturbative regime. One method of testing QCD in this low-energy region is by measuring certain structure constants of hadrons -- called polarizabilities -- that show particular promise of allowing a direct connection to the underlying quark/gluon dynamics through comparison to modern QCD-inspired model...
We will report on recently published experimental results on spin sum rules, and particularly on the generalized spin polarizabilities $\gamma_0^n(Q^2)$ and $\delta_{LT}^n(Q^2)$. The data were taken at Jefferson Lab in Hall A and B by experiments E97-110 and EG4, respectively. They covered the very low $Q^2$ domain, down to $Q^2 \sim 0.02$ GeV$^2$, where Chiral Effective Field Theory...
We will report on recently published experimental results on the proton longitudinal spin structure at long distance. The inclusive data were taken with the Jefferson Lab CLAS spectrometer in Hall B by experiment EG4. They covered the very low $Q^2$ domain, down to $Q^2 = 0.012$ GeV$^2$, where Chiral Effective Field Theory ($\chi$EFT) is applicable, thereby providing a test of its predictions.
