Tübingen 2003 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 3: Elektromagnetische und hadronische Proben I
HK 3.12: Vortrag
Montag, 17. März 2003, 19:00–19:15, B
Photoinduced production of η and η′ on nucleons — •Buḡra Borasoy, Eugenio Marco, and Stefan Wetzel — Physik Department der Technischen Universität München,Garching, Germany
The photo- and electroproduction of η, η′ mesons on nucleons are investigated within a relativistic chiral unitary approach based on coupled channels. The s-wave potentials for electroproduction and meson-baryon scattering are derived from a chiral effective Lagrangian which includes the η′ as an explicit degree of freedom and incorporates important features of the underlying QCD Lagrangian such as the axial U(1) anomaly. The effective potentials are iterated in a Bethe-Salpeter equation and cross sections for η, η′ photo- and electroproduction from nucleons are obtained. The results for the η′ photoproduction cross section on protons reproduce the appearance of an S11 resonance around 1.9 GeV observed at ELSA. The inclusion of electromagnetic form factors increases the predicted η electroproduction cross sections on the proton, providing a qualitative explanation for the hard form factor of the photocoupling amplitude observed at CLAS.
Work supported in part by the Deutsche Forschungsgemeinschaft.