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First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E, for the reaction , has been measured using a circularly polarized tagged-photon beam, with energies from 0.35 to 2.37 GeV. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer in Hall B at the Thomas Jefferson National Accelerator Facility. These polarization data agree fairly well with previous partial-wave analyses at low photon energies. Over much of the covered energy range, however, significant deviations are observed, particularly in the high-energy region where high-L multipoles contribute. The data have been included in new multipole analyses resulting in updated nucleon resonance parameters. We report updated fits from the Bonn–Gatchina, Jülich–Bonn, and SAID groups.
Available at: http://works.bepress.com/angela_biselli/132/
© 2015 The Author(s)
Published by Elsevier B.V. under CC License Attribution 4.0 International (CC BY 4.0)