30 research outputs found

    The N(1520) 3/2- helicity amplitudes from an energy-independent multipole analysis based on new polarization data on photoproduction of neutral pions

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    New data on the polarization observables T, P, and H for the reaction γppπ0\gamma p \to p\pi^0 are reported. The results are extracted from azimuthal asymmetries when a transversely polarized butanol target and a linearly polarized photon beam are used. The 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

    The polarization observables T, P, and H and their impact on γppπ0\gamma p \to p\pi^0 multipoles

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    Data on the polarization observables T, P, and H for the reaction γppπ0\gamma p\to p\pi^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 were 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 γpηp\vec{\gamma} \vec{p}\rightarrow \eta p with polarized photons and protons and their implications for NNηN^* \to N\eta decays

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    The polarization observables T,E,P,HT, E, P, H, and GG in photoproduction of η\eta mesons off protons are measured for photon energies from threshold to W=2400W=2400\,MeV (TT), 2280 MeV (EE), 1620 MeV (P,HP, H), or 1820 MeV (GG), covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, J\"uBo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the NηN\eta decay of nucleon resonances. A NηN\eta-branching ratio of 0.33±0.040.33\pm 0.04 for N(1650)1/2N(1650)1/2^- is found, which reduces the large and controversially discussed NηN\eta-branching ratio difference of the two lowest mass JP=1/2J^P=1/2^--resonances significantly.Comment: 10 pages, 11 figure
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