Research objectives and content
The theoretical study of nucleon structure will be performed by taking into account electromagnetic processes such as real and virtual photon scattering (Compton scattering) and total absorption of polarized photons on polarized nucleons, where the existence of the Cerasimov-Drell-Hearn (CDH) sum rule links the helicity structure of the cross section in the inelastic region with ground state properties of the nucleon. Both processes are under experimental investigations with the MAMI and ELSA facilities in Mainz and Bonn, respectively. In Mainz the theoretical aspects of these processes are being studied.
Compton scattering with both real and virtual photons is a
fundamental exclusive reaction which can give global information on the excitation spectrum of the hadron. It provides us with a better understanding of the baryon wave function in the non perturbative regime. Being based on very general principles, the CDH sum rule is an important consistency check for our understanding of the hadronic structure. Interest in the CDH sum rule is also motivated by its connection with the sum rules for the spin-polarized structure functions in deep inelastic scattering at high momentum transfer Q2. The Q2 dependence of the CDH integral in the resonance region is very sensitive to the spinflavor structure of the nucleon and will give us important information on the quark-gluon dynamics of the hadrons. Taking advantage of the previous work performed in a light-cone approach to hadron dynamics and combining this with the expertise of the Mainz theory group, theoretical calculations of the reaction mechanism will be achieved in terms of both quark and hadronic degrees of freedom, comparing the predictions of different nucleon structure models with the forthcoming data.
Training content (objective, benefit and expected impact)
The research project would contribute to gain a deeper theoretical understanding on the non-perturbative structure of the nucleon. The subjects proposed have received a great deal of attention, both experimentally and theoretically. In this regard the Mainz University has a leading role and will give the opportunity to the applicant to improve and develope the scientific techniques and skills acquired in the previous research activity on the relativistic constituent quark model. Links with industry / industrial relevance (22)