Speaker
Description
Generalized Parton Distributions (GPDs) are a well-established tool for the exploration of the 3D nucleon structure. While extensive studies have been performed to unravel the 3D structure of the ground-state nucleon, little is known about the 3D structure of baryon resonances. The nucleon-to-resonance transition GPDs provide a unique tool for exploring the 3D structure and mechanical properties of such resonances, reaching beyond the 2D picture provided by the widely studied transition form factors and opening the way towards a deeper understanding of baryon resonances on the partonic level. Transition GPDs can be measured in exclusive processes with nucleon to resonance transitions, like N to N deeply virtual Compton scattering and N to N deeply virtual meson production, but also formalisms for a measurement with hadronic beams, especially meson beams, exist. The talk will provide an introduction to transition GPDs and the related higher-level observables. First experimental data from the $ep \to e \Delta^{++} \pi^{-}$ deeply virtual meson production process and from the $ep \to e \Delta^{++} \gamma$ deeply virtual Compton scattering process, available from the CLAS12 experiment at Jefferson Laboratory, will be presented, and further opportunities with other channels and different target polarizations will be discussed. In addition, future opportunities to measure transition GPDs at JLAB, J-PARC, COMPASS, and the EIC will be reviewed.
*The work is partly supported by Deutsche Forschungsgemeinschaft (Project No. 508107918).
