Dispersion Theory and the Low Energy Constants for Neutral Pion Photoproduction

Abstract

The relativistic amplitudes of pion photoproduction are evaluated by dispersion relations at t=const. The imaginary parts of the amplitudes are taken from the MAID model covering the absorption spectrum up to center-of-mass energies W = 2.2 GeV. For sub-threshold kinematics the amplitudes are expanded in powers of the two independent variables νand t related to energy and momentum transfer. Subtracting the loop corrections from this power series allows one to determine the counter terms of covariant baryon chiral perturbation theory. The proposed continuation of the amplitudes into the unphysical region provides a unique framework to derive the low-energy constants to any given order as well as an estimate of the higher order terms by global properties of the absorption spectrum.

arXiv comment13 pages, 6 figures, 5 tables

References in corpus (13)

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Cited by in corpus (14)

• Chiral Perturbation Theory and Baryon Properties
• Electroexcitation of nucleon resonances
• Chiral perturbation theory
• Electromagnetic Excitation of Nucleon Resonances
• Isospin violation in the vector form factors of the nucleon
• Photoproduction of eta-mesons on the deuteron above S11(1535) in the presence of a narrow P11(1670) resonance
• The MAID Legacy and Future
• Regge phenomenology in ${\pi }^0$ and $\eta$ photoproduction
• Dispersive analysis of the Primakoff reaction $\gamma K\to K\pi$
• Invariant Amplitudes for Pion Electroproduction
• Structure of Pion Photoproduction Amplitudes
• Fixed-t analyticity as a constraint in single energy partial wave analyses of meson photoproduction reactions
• Single-Energy Partial Wave Analysis for ${\pi }^0$ Photoproduction on Proton with Fixed-$t$ Analyticity Imposed
• A dispersive approach to pion photo- and electroproduction