Beam-Target Helicity Asymmetry for γ → n → →π-p in the N∗ Resonance Region

(CLAS Collaboration)

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


We report the first beam-target double-polarization asymmetries in the γ+n(p)→π-+p(p) reaction spanning the nucleon resonance region from invariant mass W=1500 to 2300 MeV. Circularly polarized photons and longitudinally polarized deuterons in solid hydrogen deuteride (HD) have been used with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The exclusive final state has been extracted using three very different analyses that show excellent agreement, and these have been used to deduce the E polarization observable for an effective neutron target. These results have been incorporated into new partial wave analyses and have led to significant revisions for several γnN∗ resonance photocouplings.

Original languageEnglish (US)
Article number242002
JournalPhysical Review Letters
Issue number24
StatePublished - Jun 16 2017

ASJC Scopus subject areas

  • General Physics and Astronomy


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