Data on the polarization observables T, P, and H for the reaction $gamma pto ppi^0$ are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results w
ere extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. The data were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS detector. Within the Bonn-Gatchina partial wave analysis, the new polarization data lead to a significant narrowing of the error band for the multipoles for neutral-pion photoproduction.
New data on the polarization observables T, P, and H for the reaction $gamma p to ppi^0$ are reported. The results are extracted from azimuthal asymmetries when a transversely polarized butanol target and a linearly polarized photon beam are used. Th
e data were taken at the Bonn electron stretcher accelerator ELSA using the CBELSA/TAPS detector. These and earlier data are used to perform a truncated energy-independent partial wave analysis in sliced-energy bins. This energy-independent analysis is compared to the results from energy-dependent partial wave analyses.
One of the remaining problems within the standard model is to gain a good understanding of the low energy regime of QCD, where perturbative methods fail. One key towards a better understanding is baryon spectroscopy. Unfortunately, in the past most b
aryon spectroscopy data have been obtained only using $pi$ N scattering. To gain access to resonances with small $pi$ N partial width, photoproduction experiments, investigating various final states, provide essential information. In order to extract the contributing resonances, partial wave analyses need to be performed. Here, the complete experiment is required to unambiguously determine the contributing amplitudes. This involves the measurement of carefully chosen single and double polarization observables. The Crystal Barrel/TAPS experiment with a longitudinally or transversely polarized target and an energy tagged, linearly or circularly polarized photon beam allows the measurement of a large set of polarization observables. Due to its good energy resolution, high detection efficiency for photons, and the nearly complete solid angle coverage, it is ideally suited for the measurement of the photoproduction of neutral mesons decaying into photons. Preliminary results for the target asymmetry T, recoil polarization P and the double polarization observable H are discussed for $pi^{0}$ and $eta$ photoproduction off the proton.
