Z. Akbar, Florida State University
P. Roy, University of Michigan - Ann Arbor
S. Park, Korea Atomic Energy Research Institute, South Korea
V. Crede, Florida State University
A. V. Anisovich, Universität Bonn, Germany
I. Denisenko, Universität Bonn, Germany
E. Klempt, Universität Bonn, Germany
V. A. Nikonov, Universität Bonn, Germany
A. V. Sarantsev, Universität Bonn, Germany
K. P. Adhikari, Mississippi State University
S. Adhikari, Florida International University
M. J. Amaryan, Old Dominion University
S. Anefalos Pereira, Instituto Nazionale di Fisica Nucleare, Italy
H. Avakian, Thomas Jefferson National Accelerator Facility
J. Ball, Université Paris-Saclay, France
M. Battaglieri, Instituto Nazionale di Fisica Nucleare, Italy
V. Batourine, Thomas Jefferson National Accelerator Facility
I. Bedlinskiy, Institute of Theoretical and Experimental Physics, Russia
S. Boiarinov, Thomas Jefferson National Accelerator Facility
W. J. Briscoe, The George Washington University
J. Brock, Thomas Jefferson National Accelerator Facility
W. K. Brooks, Thomas Jefferson National Accelerator Facility
V. D. Burkert, Thomas Jefferson National Accelerator Facility
F. T. Cao, University of Connecticut
C. Carlin, Thomas Jefferson National Accelerator Facility
D. S. Carman, Thomas Jefferson National Accelerator Facility
A. Celentano, Instituto Nazionale di Fisica Nucleare, Italy
G. Charles, Old Dominion University
T. Chetry, Ohio University
G. Ciullo
Wesley P. Gohn, University of KentuckyFollow


The double-polarization observable E was studied for the reaction γp 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, ωπ+ππ0, using a circularly polarized tagged-photon beam with energies ranging from the ω 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 subthreshold N(1720)3/2+ nucleon resonance. To describe the entire data set, which consisted of ω differential cross sections and a large variety of polarization observables, further contributions from other nucleon resonances were found to be necessary. With respect to nonresonant mechanisms, π 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 ≈ 2 GeV.

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Published in Physical Review C, v. 96, issue 6, 065209, p. 1-11.

©2017 American Physical Society

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Due to the large number of authors, only the first 30 and the authors affiliated with the University of Kentucky are listed in the author section above. For the complete list of authors, please download this article or visit:

This group of authors is collectively known as the CLAS Collaboration.

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This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177. This work was also supported by the U.S. National Science Foundation, the State Committee of Science of the Republic of Armenia, the Chilean Comisión Nacional de Investigación Científica y Tecnológica (CONICYT), the Italian Istituto Nazionale di Fisica Nucleare, the French Centre National de la Recherche Scientifique, the French Commissariat a l’Energie Atomique, the Scottish Universities Physics Alliance (SUPA), the United Kingdom’s Science and Technology Facilities Council, the National Research Foundation of Korea, the Deutsche Forschungsgemeinschaft (SFB/TR110), and the Russian Science Foundation under Grant No. 16-12-10267.

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