Original scientific paper

Spin observables in pion photoproduction from a unitary and causal effective field theory

A. M. Gasparyan ; GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstrasse 1, 64291 Darmstadt, Germany
M. F. M. Lutz ; SSC RF ITEP, Bolshaya Cheremushkinskaya 25, 117218 Moscow, Russia

Abstract

Pion photoproduction is analyzed with the chiral Lagrangian. Partial-wave amplitudes are obtained by an analytic extrapolation of sub-threshold reaction amplitudes computed in chiral perturbation theory, where the constraints set by electromagnetic-gauge invariance, causality and unitarity are used to stabilize the extrapolation. The experimental data set is reproduced up to energies √ s ≃ 1300 MeV in terms of the parameters relevant at order Q3 . We present and discuss predictions for various spin observables.

Keywords

pion photoproduction; chiral perturbation theory; stabilization of extrapolation; spin observables

Hrčak ID:

304630

URI

https://hrcak.srce.hr/304630

Publication date:

1.3.2011.

Article data in other languages: croatian

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