Coherent π° Photoproduction in the Isobar-Hole Formalism
Coherent π° photoproduction is expected to provide a rather clean test of our understanding of the pion optical potential. As a production reaction, it is sensitive to the pion wavefunction inside the nucleus and not just to the phase shifts measured in elastic pion scattering. As a photoreaction, the reaction mechanism is comparatively well understood. Previous calculations have used the standard DWIA approach with a first order pion optical potential. These do not agree with the somewhat ancient data available for production in the resonance region. Recently, the isobar-hole formalism1-4 has led to a detailed and quite successful description for π-160 scattering in the resonance region, and our aim in this note is to show some results of applying the same formalism to the coherent 160(γ,π°) 160 reaction. We shall discuss the way in which the isobar-hole formalism goes beyond the DWIA framework and the extent to which the (γ,π°) cross section is sensitive to different phase-shift-equivalent descriptions of the pion-nucleus dynamics.
KeywordsPartial Wave Clean Test Nuclear Ground State Doorway State Plane Wave Impulse Approximation
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Notes and References
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