Experimental tests of Chiral Perturbation Theory
Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099, Mainz, Germany
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Accepted: 12 May 2006
Published online: 15 May 2006
Over the last decade, a series of dedicated experiments to test heavy baryon chiral perturbation theory was performed at MAMI. Photo production of neutral pions close to threshold with unpolarized and polarized photon beam was performed to separate the multipole amplitudes at threshold. The extension of this experiments to a modest photon virtuality of Q 2 < 0.1 GeV^2/c 2 was performed to extract additional longitudinal multipoles and to exploit the Q2 evolution predicted by theory. An out-of-plane measurement above π+ threshold with polarized electron beam gave access to the imaginary part of the s-wave amplitude. Finally, by coherent photo and electro production from the deuteron the neutron amplitude could be extracted.
PACS: 25.30.Rw Electroproduction reactions – / 13.60.Le Meson production – / 12.39.Fe Chiral Lagrangians –
© Società Italiana di Fisica and Springer-Verlag, 2006