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Fanelli C, Cisbani E, Hamilton DJ, Salmé G, Wojtsekhowski B, Ahmidouch A, Annand JRM, Baghdasaryan H, Beaufait J, Bosted P, Brash EJ, Butuceanu C, Carter P, Christy E, Chudakov E, Danagoulian S, Day D, Degtyarenko P, Ent R, Fenker H, Fowler M, Frlez E, Gaskell D, Gilman R, Horn T, Huber GM, de Jager CW, Jensen E, Jones MK, Kelleher A, Keppel C, Khandaker M, Kohl M, Kumbartzki G, Lassiter S, Li Y, Lindgren R, Lovelace H, Luo W, Mack D, Mamyan V, Margaziotis DJ, Markowitz P, Maxwell J, Mbianda G, Meekins D, Meziane M, Miller J, Mkrtchyan A, Mkrtchyan H, Mulholland J, Nelyubin V, Pentchev L, Perdrisat CF, Piasetzky E, Prok Y, Puckett AJR, Punjabi V, Shabestari M, Shahinyan A, Slifer K, Smith G, Solvignon P, Subedi R, Wesselmann FR, Wood S, Ye Z, Zheng X. Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton. Phys Rev Lett 2015; 115:152001. [PMID: 26550716 DOI: 10.1103/physrevlett.115.152001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Indexed: 06/05/2023]
Abstract
Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θ_{cm}^{p}=70°. The longitudinal transfer K_{LL}, measured to be 0.645±0.059±0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.
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Affiliation(s)
- C Fanelli
- Dipartimento di Fisica, Università La Sapienza, Rome, Italy and INFN, Sezione di Roma, 00185 Rome, Italy
- INFN, Sezione di Roma, gruppo Sanità and Istituto Superiore di Sanità, 00161 Rome, Italy
| | - E Cisbani
- INFN, Sezione di Roma, gruppo Sanità and Istituto Superiore di Sanità, 00161 Rome, Italy
| | - D J Hamilton
- University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - G Salmé
- Dipartimento di Fisica, Università La Sapienza, Rome, Italy and INFN, Sezione di Roma, 00185 Rome, Italy
| | - B Wojtsekhowski
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - A Ahmidouch
- North Carolina A&T State University, Greensboro, North Carolina 27411, USA
| | - J R M Annand
- University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - H Baghdasaryan
- University of Virginia, Charlottesville, Virginia 22904, USA
| | - J Beaufait
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - P Bosted
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - E J Brash
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
- Christopher Newport University, Newport News, Virginia 23606, USA
| | - C Butuceanu
- University of Regina, Regina, Saskatchewan S4S OA2, Canada
| | - P Carter
- Christopher Newport University, Newport News, Virginia 23606, USA
| | - E Christy
- Hampton University, Hampton, Virginia 23668, USA
| | - E Chudakov
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - S Danagoulian
- North Carolina A&T State University, Greensboro, North Carolina 27411, USA
| | - D Day
- University of Virginia, Charlottesville, Virginia 22904, USA
| | - P Degtyarenko
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - R Ent
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - H Fenker
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - M Fowler
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - E Frlez
- University of Virginia, Charlottesville, Virginia 22904, USA
| | - D Gaskell
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - R Gilman
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
- Rutgers, The State University of New Jersey, Piscataway, New Jersey 08855, USA
| | - T Horn
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - G M Huber
- University of Regina, Regina, Saskatchewan S4S OA2, Canada
| | - C W de Jager
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
- University of Virginia, Charlottesville, Virginia 22904, USA
| | - E Jensen
- Christopher Newport University, Newport News, Virginia 23606, USA
| | - M K Jones
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - A Kelleher
- College of William and Mary, Williamsburg, Virginia 23187, USA
| | - C Keppel
- Hampton University, Hampton, Virginia 23668, USA
| | - M Khandaker
- Norfolk State University, Norfolk, Virginia 23504, USA
| | - M Kohl
- Hampton University, Hampton, Virginia 23668, USA
| | - G Kumbartzki
- Rutgers, The State University of New Jersey, Piscataway, New Jersey 08855, USA
| | - S Lassiter
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - Y Li
- Hampton University, Hampton, Virginia 23668, USA
| | - R Lindgren
- University of Virginia, Charlottesville, Virginia 22904, USA
| | - H Lovelace
- Norfolk State University, Norfolk, Virginia 23504, USA
| | - W Luo
- Lanzhou University, Lanzhou 730000, Gansu, People's Republic of China
| | - D Mack
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - V Mamyan
- University of Virginia, Charlottesville, Virginia 22904, USA
| | - D J Margaziotis
- California State University Los Angeles, Los Angeles, California 90032, USA
| | - P Markowitz
- Florida International University, Miami, Florida 33199, USA
| | - J Maxwell
- University of Virginia, Charlottesville, Virginia 22904, USA
| | - G Mbianda
- University of Witwatersrand, Johannesburg, South Africa
| | - D Meekins
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - M Meziane
- College of William and Mary, Williamsburg, Virginia 23187, USA
| | - J Miller
- University of Maryland, College Park, Maryland 20742, USA
| | - A Mkrtchyan
- Yerevan Physics Institute, Yerevan 375036, Armenia
| | - H Mkrtchyan
- Yerevan Physics Institute, Yerevan 375036, Armenia
| | - J Mulholland
- University of Virginia, Charlottesville, Virginia 22904, USA
| | - V Nelyubin
- University of Virginia, Charlottesville, Virginia 22904, USA
| | - L Pentchev
- College of William and Mary, Williamsburg, Virginia 23187, USA
| | - C F Perdrisat
- College of William and Mary, Williamsburg, Virginia 23187, USA
| | - E Piasetzky
- University of Tel Aviv, Tel Aviv 6997801, Israel
| | - Y Prok
- Christopher Newport University, Newport News, Virginia 23606, USA
| | - A J R Puckett
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - V Punjabi
- Norfolk State University, Norfolk, Virginia 23504, USA
| | - M Shabestari
- University of Virginia, Charlottesville, Virginia 22904, USA
| | - A Shahinyan
- Yerevan Physics Institute, Yerevan 375036, Armenia
| | - K Slifer
- University of Virginia, Charlottesville, Virginia 22904, USA
| | - G Smith
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - P Solvignon
- Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - R Subedi
- University of Virginia, Charlottesville, Virginia 22904, USA
| | | | - S Wood
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - Z Ye
- Hampton University, Hampton, Virginia 23668, USA
| | - X Zheng
- University of Virginia, Charlottesville, Virginia 22904, USA
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