27 research outputs found

    Nucleon resonances in the fourth resonance region

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    Nucleon and Δ\Delta resonances in the fourth resonance region are studied in a multichannel partial-wave analysis which includes nearly all available data on pion- and photo-induced reactions off protons. In the high-mass range, above 1850\,MeV, several alternative solutions yield a good description of the data. For these solutions, masses, widths, pole residues and photo-couplings are given. In particular, we find evidence for nucleon resonances with spin-parities JP=1/2+...7/2+J^P=1/2^+...7/2^+. For one set of solutions, there are four resonances forming naturally a spin-quartet of resonances with orbital angular momentum L=2 and spin S=3/2 coupling to J=1/2,...,7/2J=1/2,...,7/2. Just below 1.9\,GeV we find a spin doublet of resonances with JP=1/2J^P=1/2^- and 3/23/2^-. Since a spin partner with JP=5/2J^P=5/2^- is missing at this mass, the two resonances form a spin doublet which must have a symmetric orbital-angular-momentum wave function with L=1. For another set of solutions, the four positive-parity resonances are accompanied by mass-degenerate negative-parity partners -- as suggested by the conjecture of chiral symmetry restoration. The possibility of a JP=1/2+,3/2+J^P=1/2^+, 3/2^+ spin doublet at 1900\,MeV belonging to a 20-plet is discussed.Comment: 16 page

    Properties of baryon resonances from a multichannel partial wave analysis

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    Properties of nucleon and Δ\Delta resonances are derived from a multichannel partial wave analysis. The statistical significance of pion and photo-induced inelastic reactions off protons are studied in a multichannel partial-wave analysis.Comment: 12 pages, 8 Table
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