Invariant amplitudes for pion electroproduction |
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Authors: | B. Pasquini D. Drechsel L. Tiator |
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Affiliation: | 1.Dipartimento di Fisica Nucleare e Teorica,Università degli Studi di Pavia and INFN, Sezione di Pavia,Pavia,Italy;2.Institut für Kernphysik,Johannes Gutenberg-Universit?t,Mainz,Germany |
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Abstract: | The invariant amplitudes for pion electroproduction on the nucleon are evaluated by dispersion relations at constant t with MAID as input for the imaginary parts of these amplitudes. In the threshold region these amplitudes are confronted with the predictions of several low-energy theorems derived in the soft-pion limit. In general agreement with chiral perturbation theory, the dispersive approach yields large corrections to these theorems because of the finite pion mass. |
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Keywords: | 11.55.Fv Dispersion relations 11.55.Hx Sum rules 13.40.Gp Electromagnetic form factors 13.60.Le Meson production |
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