Speaker
Description
QCD provides a rich spectrum of excited baryon states. The understanding of their internal structure is of essential important for many fields of nuclear physics, such as nuclear forces, dense matter or neutrino-nucleus interactions. It is known, that Generalized Parton Distributions (GPDs) are a well established tool for characterizing the QCD structure of the ground-state nucleon based on 3D tomographic images of the quark/gluon structure and provide direct relations between the internal structure and the mechanical properties of the system. Transition GPDs extend these concepts to N→N$^∗$ transitions and can be used to characterize the 3D structure and mechanical properties of baryon resonances. They can be probed for example in high-momentum transfer exclusive electroproduction processes with resonance transitions e+N→e+M+N$^*$, such as deeply virtual Compton scattering (M = γ) or meson production (M = π, K …). Based on the high-intensity, 10.6 GeV electron beam at JLAB and the large acceptance CLAS12 spectrometer, it becomes possible to study these processes in a large kinematic range. The talk will provide an overview on the experimental results in the field, with a special focus on results of the deeply virtual ep→eΔ$^{++}$π$^-$ and ep→eΔ$^0$π$^+$ processes and discuss the feasibility of the study of further N→N$^*$ DVMP processes with CLAS12. Furthermore, first results for beam spin asymmetries of the N→N$^*$ DVCS process (ep→eN$^*$+γ) will be presented and compared to transition GPD based theory predictions. As an outlook, future perspectives with the EIC and a 22 GeV JLAB upgrade will be presented.
*The work is partly supported by Deutsche Forschungsgemeinschaft (Project No. 508107918).