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AbstractAbstract
[en] The spectrum and the properties of baryon resonances can be studied using photons with energies appropriate to excite baryonic states. Double meson photoproduction allows access to cascading resonance decays via other excited states. Also, at higher energies the importance of the double meson photoproduction increases due to higher cross-sections in comparison to single meson photoproduction. To study baryon resonances, the measurement of polarization observables as well as the measurement of differential cross-sections plays a very important role. In this work the three-body polarization observables Is, Ic and the respective twobody asymmetry Σ were measured for the reaction γp → pπ0π0 in an incoming photon energy range of Eγ = 970 - 1650 MeV. The data were acquired with the CBELSA/TAPS experiment located at the ELSA accelerator in Bonn, using a linearly polarized photon beam impinging on a liquid hydrogen target. The observables Is and Ic which occur in two-meson final states are measured for the first time in the reaction γp → pπ0π0. The corresponding two-body asymmetry Σ is measured in an extended energy range in comparison to already existing data. A comparison with theoretical models shows that the polarization observables provide valuable input to study resonance contributions and their decay modes. The D33(1700) → Δπ decay is studied based on the comparison of the Bonn-Gatchina Partial Wave Analysis (PWA) predictions with the data. Furthermore, a comparison of the data with the Bonn-Gatchina PWA and the Fix isobar model predictions allows to distinguish between these two models. Additionally, band-like structures and peaks are observed in the mass ranges of Δ(1232), D13(1520), F15(1680), f0(980) and f2(1270) in the according Dalitz plots and invariant mass distributions. The contributions of these states are confirmed by the Bonn-Gatchina PWA. An excellent compatibility with the existing data from the previous CBELSA experiment is observed.
Primary Subject
Source
27 Jul 2012; 197 p; Diss. (Dr.rer.nat.)
Record Type
Miscellaneous
Literature Type
Thesis/Dissertation; Numerical Data
Report Number
Country of publication
DALITZ PLOT, DELTA-1232 BARYONS, DELTA-1700 BARYONS, EFFECTIVE MASS, EXPERIMENTAL DATA, F0-980 MESONS, F2-1270 MESONS, GEV RANGE 01-10, HADRONIC PARTICLE DECAY, MASS SPECTRA, MEV RANGE 100-1000, N-1535 BARYONS, N-1680 BARYONS, PAIR PRODUCTION, PHOTON-PROTON INTERACTIONS, PHOTOPRODUCTION, PIONS NEUTRAL, POLARIZATION-ASYMMETRY RATIO, POLARIZED BEAMS, PROTONS
BARYONS, BASIC INTERACTIONS, BEAMS, BOSONS, DATA, DECAY, DELTA BARYONS, DIAGRAMS, DIMENSIONLESS NUMBERS, ELECTROMAGNETIC INTERACTIONS, ELEMENTARY PARTICLES, ENERGY RANGE, FERMIONS, GEV RANGE, HADRONS, INFORMATION, INTERACTIONS, MASS, MESONS, MEV RANGE, N BARYONS, N*BARYONS, NUCLEONS, NUMERICAL DATA, PARTICLE DECAY, PARTICLE INTERACTIONS, PARTICLE PRODUCTION, PHOTON-BARYON INTERACTIONS, PHOTON-HADRON INTERACTIONS, PHOTON-NUCLEON INTERACTIONS, PIONS, PSEUDOSCALAR MESONS, SCALAR MESONS, SCATTERPLOTS, SPECTRA, TENSOR MESONS
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