Physics Letters B
First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E, for the reaction ɣ→p→→π+n, 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, Jfilich-Bonn, and SAID groups.
Original Publication Citation
Strauch, S., Briscoe, W. J., Doring, M., Klempt, E., Nikonov, V. A., Pasyuk, E., . . . Collaboration, C. (2015). First measurement of the polarization observable E in the p→ (ɣ→, π+) in reaction up to 2.25 GeV. Physics Letters B, 750, 53-58. doi: 10.1016/j.physletb.2015.08.053
Strauch, S.; Briscoe, W. J.; Döring, M.; Klempt, E.; Nikonov, V. A.; Pasyuk, E.; Rönchen, D.; Sarantsev, A.V.; Strakovsky, I.; Workman, R.; Adhikari, K. P.; Adikaram, D.; and Fassi, L. El, "First Measurement of the Polarization Observable E in the p→ (ɣ→, π+) in Reaction up to 2.25 Gev" (2015). Physics Faculty Publications. 45.