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Title: Measurement of the helicity asymmetry E in ω π+ π- π0 photoproduction

Journal Article · · Physical Review C
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The double-polarization observable $$E$$ was studied for the reaction $$\gamma p\to p\omega$$ using the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B at the Thomas Jefferson National Accelerator Facility and the longitudinally-polarized frozen-spin target (FROST). The observable was measured from the charged decay mode of the meson, $$\omega\to\pi^+\pi^-\pi^0$$, using a circularly-polarized tagged-photon beam with energies ranging from the $$\omega$$ threshold at 1.1 to 2.3 GeV. A partial-wave analysis within the Bonn-Gatchina framework found dominant contributions from the $3/2^+$ partial wave near threshold, which is identified with the sub-threshold $$N(1720)\,3/2^+$$ nucleon resonance. To describe the entire data set, which consisted of $$\omega$$ differential cross sections and a large variety of polarization observables, further contributions from other nucleon resonances were found to be necessary. Here, with respect to non-resonant mechanisms, $$\pi$$ exchange in the $$t$$-channel was found to remain small across the analyzed energy range, while pomeron $$t$$-channel exchange gradually grew from the reaction threshold to dominate all other contributions above $$W \approx 2$$ GeV.

Research Organization:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Contributing Organization:
The CLAS Collaboration
Grant/Contract Number:
AC05-06OR23177
OSTI ID:
1416533
Alternate ID(s):
OSTI ID: 1416450; OSTI ID: 1439827
Report Number(s):
JLAB-PHY--17-2532; DOE/OR/23177--4227; arXiv:1708.02608
Journal Information:
Physical Review C, Journal Name: Physical Review C Journal Issue: 6 Vol. 96; ISSN PRVCAN; ISSN 2469-9985
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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Polarized ultrashort brilliant multi-GeV $γ$-rays via single-shot laser-electron interaction text January 2019
Nucleon resonances in γ p → ω p reaction journal December 2019
Polarized Ultrashort Brilliant Multi-GeV γ Rays via Single-Shot Laser-Electron Interaction journal January 2020