### Research areas

- Experimental hadron physics
- Theoretical hadron physics

### Principal investigators

### Goals

The excitation spectra of hadrons reflect the underlying strong dynamics complementary to polarizabilities, elastic form factors and parton distributions. In this project we will focus on the following topics:

**Meson photoproduction**

Recently, new high precision cross section and polarization data in meson photoproduction have become the broadest source of information about excited baryons. Several groups try to describe these new data with reaction models and try to understand the resonance contributions. We will contribute to these efforts by providing preliminary MAMI data and by refining the MAID model. However, the main focus is a unique extraction of partial wave amplitudes without assuming any reaction model. Significant data sets for this analysis will be obtained in a combined effort at MAMI and ELSA using the Mainz polarized target at both accelerators in the most efficient way.**Baryon resonances in J/\(\mathbf{\psi}\) decays**

High statistics BESIII data on the decays \(J/\psi \to p \bar p \pi^0/p \bar p\eta\) and \(J/\psi (\psi^\prime) \to \bar p n \pi^+ / p \bar n \pi^-\)will allow us to independently confirm resonance properties determined from photoproduction data. This is an important task especially in the case of new high mass states as well as in case of the Roper-resonance, whose dynamical origin is still intensely discussed. We plan to reconstruct these decays using the full available statistics of the \(J/\psi\) and \(\psi^\prime\)datasets from BESIII and to perform an amplitude analysis for the interpretation.