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HK: Fachverband Physik der Hadronen und Kerne

HK 29: Elektromagnetische und Hadronische Sonden

HK 29.3: Talk

Wednesday, March 14, 2007, 14:45–15:00, A

Recent results in the dispersion-theoretical analysis of the nucleon form factors — •Maxim Belushkin, Hans-Werner Hammer, and Ulf Meißner — Helmholz-Institut für Strahlen- und Kernphysik, Nußallee 14-16, Bonn, 53115 Germany

Dispersion relations provide a powerful nonperturbative tool to analyse the form factors of the nucleon for all momentum transfers. Constraints from meson-nucleon scattering, unitarity, and perturbative QCD can be included in a straightforward way. In particular, we include the 2π, ρπ and the KK continua as independent input in our analysis, and provide errors bands on the results. We have explored two methods for including asymptotic constraints from perturbative QCD, and have analysed the world data on all four form factors in both the space- and the time-like regions simultaneously. Moreover, we have extracted the nucleon radii and the meson-nucleon coupling constants for the ω and the ρ mesons. For the radii, we generally find a good agreement with other determinations, with the exception of the electric charge radius of the proton.