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arXiv · 1010.4192

Unitary and causal dynamics based on the chiral Lagrangian

A. M. Gasparyan·M. F. M. Lutz
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Abstract

Pion-nucleon scattering, pion photoproduction, and nucleon Compton scattering are analyzed within a scheme based on the chiral Lagrangian. Partial-wave amplitudes are obtained by an analytic extrapolation of subthreshold reaction amplitudes computed in chiral perturbation theory, where the constraints set by electromagnetic-gauge invariance, causality and unitarity are used to stabilize the extrapolation. Experimental data are reproduced up to energies $\sqrt{s}\simeq 1300$ MeV in terms of the parameters relevant at order $Q^3$. A striking puzzle caused by an old photon asymmetry measurement close to the pion production threshold is discussed.

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A. M. Gasparyan, M. F. M. Lutz. 2010-10-20. Unitary and causal dynamics based on the chiral Lagrangian. https://doi.org/10.1063/1.3541986

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