Nucleon Resonances: From Photoproduction to High Photon Virtualities

The workshop will be devoted to the study of the nucleon resonance spectrum and structure as it becomes accessible through the electromagnetic excitation of the nucleon (EmNN*) in exclusive meson production. It will focus on: (a) the baryon spectrum in exclusive meson photoproduction, (b) the search for new baryon states in combined studies of exclusive photo- and electroproduction, (c) electroexcited N* states and their structure at photon virtualities up to 5 GeV2, and (d) the extension of these studies in the near future up to 12 GeV2. This will give us the unique opportunity to establish the baryon spectrum from experimental photoproduction data under minimal model dependence as well as to explore the complex interplay of quark-gluon and meson-baryon degrees of freedom in the N* structure and the transition from quark-gluon confinement towards perturbative QCD as it is revealed in the structure of excited nucleons with different quantum numbers. The workshop will focus particularly on new results from ELSA, JLab, and MAMI and the development of future strategies, methods, and approaches to extract, predict, and understand the baryon spectrum and its EmNN* photo- and electrocouplings based on QCD. It will thus address key problems of contemporary hadron physics: dynamical generation of hadron mass by strong interaction in the non-perturbative regime, dynamical breaking of the QCD Lagrangian symmetries, and the nature of quark-gluon confinement in light baryons. The workshop aims to strengthen already existing, and to initiate new, international collaborations, particularly with EU research institutions and universities, and to create opportunities to facilitate and stimulate further discussions and growth in this field.