Abstract
We investigate pion photoproduction off the proton in a manifestly gauge-invariant chiral unitary extension of chiral perturbation theory. In a first step, we consider meson-baryon scattering taking into account all next-to-leading order contact interactions. The resulting low-energy constants are determined by a fit to s-wave pion-nucleon scattering and the low-energy data for the reaction π-p → ηn. Having determined the low-energy constants, we then analyse the data on the s-wave multipole amplitudes E0+ of pion and eta photoproduction. These are parameter-free predictions, as the two new low-energy constants are determined by the neutron and proton magnetic moments.
Highlights
Introduction and SummaryPseudoscalar meson photoproduction off protons is one of the premier tools to unravel the spectrum and properties of baryons made of the light up, down and strange quarks, as witnessed e.g. by the dedicated baryon resonance programs at ELSA (Bonn) and CEBAF (Jefferson Laboratory)
We investigate pion photoproduction off the proton in a manifestly gauge-invariant chiral unitary extension of chiral perturbation theory
In the second step we utilize a gauge-invariant chiral unitary coupled-channel approach as it was already applied to kaon[5] and eta[6] photoproduction based on the leading order chiral effective Lagrangian
Summary
Introduction and SummaryPseudoscalar meson photoproduction off protons is one of the premier tools to unravel the spectrum and properties of baryons made of the light up, down and strange quarks, as witnessed e.g. by the dedicated baryon resonance programs at ELSA (Bonn) and CEBAF (Jefferson Laboratory). The resulting low-energy constants are determined by a fit to s-wave pion-nucleon scattering and the low-energy data for the reaction π−p → ηn. Having determined the low-energy constants, we analyse the data on the s-wave multipole amplitudes E0+ of pion and eta photoproduction.
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