Conveners
PWG - 5
- Eric Voutier (Université Paris-Saclay - CNRS/IN2P3/IJCLab)
The beam-normal spin asymmetry from polarized positron scattering is investigated in the energy regime 1−150 MeV by means of the phase-shift analysis. The nonperturbative consideration of QED effects leads to spin-asymmetry changes of a few percent irrespective of the target nucleus. Corrections from low-lying transient nuclear excitations depend strongly on the collision geometry and the...
Accessing the contribution of hard two-photon exchange (TPE) in elastic scattering is one of the primary physics goals of the Jefferson Lab positron program. While asymmetries between positron- and electron-scattering provide direct access to TPE, there are other, pure electron observables that are sensitive to TPE, particularly normal single-spin asymmetries. In this talk, I present the...
The Mainz Energy-recovering Superconducting Accelerator (MESA) is a cutting-edge facility designed to push the frontiers of particle, hadron, and nuclear physics. It will enable high-precision measurements, including the weak mixing angle at low energies, and contribute to beyond Standard Model physics. The two main MESA's experiments, P2 and MAGIX, will provide crucial insights into nucleon...
The longest-range weak pion-nucleon coupling constant, h_π^1, is important for nuclear parity violation. Prospects of a new measurement of h_π^1 in a theoretically clean process are presented. A measurement of the parity-violating asymmetry in pion photoproduction off the proton is related to h_π^1 in a low-energy theorem of the photon polarization asymmetry at threshold in the chiral limit. A...
The electromagnetic polarizabilities are fundamental properties of the proton that characterize its response to an external EM field. The generalization of the EM polarizabilities to non-zero four-momentum transfer opens up a powerful path to study the internal structure of the proton. They map out the spatial distribution of the polarization densities in the proton, provide access to key...
