1
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Afzal F, Spieker K, Hurck P, Abt S, Achenbach P, Adlarson P, Ahmed Z, Akondi CS, Annand JRM, Arends HJ, Bashkanov M, Beck R, Biroth M, Borisov N, Braghieri A, Briscoe WJ, Cividini F, Collicott C, Costanza S, Denig A, Dieterle M, Downie EJ, Drexler P, Fegan S, Gardner S, Ghosal D, Glazier DI, Gorodnov I, Gradl W, Gurevich D, Heijkenskjöld L, Hornidge D, Huber GM, Kashevarov VL, Kay SJD, Korolija M, Krusche B, Lazarev A, Livingston K, Lutterer S, MacGregor IJD, Macrae RG, Manley DM, Martel PP, Miskimen R, Mocanu M, Mornacchi E, Mullen C, Neganov A, Neiser A, Oberle M, Ostrick M, Otte PB, Paudyal D, Pedroni P, Powell A, Reicherz G, Rostomyan T, Sfienti C, Sokhoyan V, Steffen O, Strakovsky II, Strub T, Supek I, Thiel A, Thiel M, Thomas A, Usov YA, Wagner S, Walford NK, Watts DP, Werthmüller D, Wettig J, Witthauer L, Wolfes M, Zachariou N. First Measurement Using Elliptically Polarized Photons of the Double-Polarization Observable E for γp→pπ^{0} and γp→nπ^{+}. Phys Rev Lett 2024; 132:121902. [PMID: 38579200 DOI: 10.1103/physrevlett.132.121902] [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: 07/18/2023] [Revised: 01/31/2024] [Accepted: 02/02/2024] [Indexed: 04/07/2024]
Abstract
We report the measurement of the helicity asymmetry E for the pπ^{0} and nπ^{+} final states using, for the first time, an elliptically polarized photon beam in combination with a longitudinally polarized target at the Crystal Ball experiment at MAMI. The results agree very well with data that were taken with a circularly polarized photon beam, showing that it is possible to simultaneously measure polarization observables that require linearly (e.g., G) and circularly polarized photons (e.g., E) and a longitudinally polarized target. The new data cover a photon energy range 270-1400 MeV for the pπ^{0} final state (230-842 MeV for the nπ^{+} final state) and the full range of pion polar angles, θ, providing the most precise measurement of the observable E. A moment analysis gives a clear observation of the pη cusp in the pπ^{0} final state.
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Affiliation(s)
- F Afzal
- Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, D-53115 Bonn, Germany
| | - K Spieker
- Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, D-53115 Bonn, Germany
| | - P Hurck
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - S Abt
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - P Achenbach
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - P Adlarson
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - Z Ahmed
- University of Regina, Regina, SK S4S0A2, Canada
| | - C S Akondi
- Kent State University, Kent, Ohio 44242, USA
| | - J R M Annand
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - H J Arends
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - M Bashkanov
- Department of Physics, University of York, Heslington, York, Y010 5DD, United Kingdom
| | - R Beck
- Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, D-53115 Bonn, Germany
| | - M Biroth
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - N Borisov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - A Braghieri
- INFN Sezione di Pavia, I-27100 Pavia, Pavia, Italy
| | - W J Briscoe
- Center for Nuclear Studies, The George Washington University, Washington, DC 20052, USA
| | - F Cividini
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - C Collicott
- Department of Astronomy and Physics, Saint Mary's University, E4L1E6 Halifax, Canada
| | - S Costanza
- INFN Sezione di Pavia, I-27100 Pavia, Pavia, Italy
- Dipartimento di Fisica, Università di Pavia, I-27100 Pavia, Italy
| | - A Denig
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - M Dieterle
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - E J Downie
- Center for Nuclear Studies, The George Washington University, Washington, DC 20052, USA
| | - P Drexler
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
- II. Physikalisches Institut, University of Giessen, D-35392 Giessen, Germany
| | - S Fegan
- Department of Physics, University of York, Heslington, York, Y010 5DD, United Kingdom
| | - S Gardner
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - D Ghosal
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - D I Glazier
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - I Gorodnov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - W Gradl
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - D Gurevich
- Institute for Nuclear Research, RU-125047 Moscow, Russia
| | - L Heijkenskjöld
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - D Hornidge
- Mount Allison University, Sackville, New Brunswick E4L1E6, Canada
| | - G M Huber
- University of Regina, Regina, SK S4S0A2, Canada
| | - V L Kashevarov
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - S J D Kay
- Department of Physics, University of York, Heslington, York, Y010 5DD, United Kingdom
| | - M Korolija
- Rudjer Boskovic Institute, HR-10000 Zagreb, Croatia
| | - B Krusche
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - A Lazarev
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - K Livingston
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - S Lutterer
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - I J D MacGregor
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - R G Macrae
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - D M Manley
- Kent State University, Kent, Ohio 44242, USA
| | - P P Martel
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
- Mount Allison University, Sackville, New Brunswick E4L1E6, Canada
| | - R Miskimen
- University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - M Mocanu
- Department of Physics, University of York, Heslington, York, Y010 5DD, United Kingdom
| | - E Mornacchi
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - C Mullen
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - A Neganov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - A Neiser
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - M Oberle
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - M Ostrick
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - P B Otte
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - D Paudyal
- University of Regina, Regina, SK S4S0A2, Canada
| | - P Pedroni
- INFN Sezione di Pavia, I-27100 Pavia, Pavia, Italy
| | - A Powell
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - G Reicherz
- Institut für Experimentalphysik, Ruhr Universität, 44780 Bochum, Germany
| | - T Rostomyan
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - C Sfienti
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - V Sokhoyan
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - O Steffen
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - I I Strakovsky
- Center for Nuclear Studies, The George Washington University, Washington, DC 20052, USA
| | - T Strub
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - I Supek
- Rudjer Boskovic Institute, HR-10000 Zagreb, Croatia
| | - A Thiel
- Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, D-53115 Bonn, Germany
| | - M Thiel
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - A Thomas
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - Yu A Usov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - S Wagner
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - N K Walford
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - D P Watts
- Department of Physics, University of York, Heslington, York, Y010 5DD, United Kingdom
| | - D Werthmüller
- Department of Physics, University of York, Heslington, York, Y010 5DD, United Kingdom
| | - J Wettig
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - L Witthauer
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - M Wolfes
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - N Zachariou
- Department of Physics, University of York, Heslington, York, Y010 5DD, United Kingdom
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2
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Li R, Sparveris N, Atac H, Jones MK, Paolone M, Akbar Z, Gayoso CA, Berdnikov V, Biswas D, Boer M, Camsonne A, Chen JP, Diefenthaler M, Duran B, Dutta D, Gaskell D, Hansen O, Hauenstein F, Heinrich N, Henry W, Horn T, Huber GM, Jia S, Joosten S, Karki A, Kay SJD, Kumar V, Li X, Li WB, Liyanage AH, Malace S, Markowitz P, McCaughan M, Meziani ZE, Mkrtchyan H, Morean C, Muhoza M, Narayan A, Pasquini B, Rehfuss M, Sawatzky B, Smith GR, Smith A, Trotta R, Yero C, Zheng X, Zhou J. Measured proton electromagnetic structure deviates from theoretical predictions. Nature 2022; 611:265-270. [PMID: 36261531 DOI: 10.1038/s41586-022-05248-1] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 08/17/2022] [Indexed: 11/09/2022]
Abstract
The visible world is founded on the proton, the only composite building block of matter that is stable in nature. Consequently, understanding the formation of matter relies on explaining the dynamics and the properties of the proton's bound state. A fundamental property of the proton involves the response of the system to an external electromagnetic field. It is characterized by the electromagnetic polarizabilities1 that describe how easily the charge and magnetization distributions inside the system are distorted by the electromagnetic field. Moreover, the generalized polarizabilities2 map out the resulting deformation of the densities in a proton subject to an electromagnetic field. They disclose essential information about the underlying system dynamics and provide a key for decoding the proton structure in terms of the theory of the strong interaction that binds its elementary quark and gluon constituents. Of particular interest is a puzzle in the electric generalized polarizability of the proton that remains unresolved for two decades2. Here we report measurements of the proton's electromagnetic generalized polarizabilities at low four-momentum transfer squared. We show evidence of an anomaly to the behaviour of the proton's electric generalized polarizability that contradicts the predictions of nuclear theory and derive its signature in the spatial distribution of the induced polarization in the proton. The reported measurements suggest the presence of a new, not-yet-understood dynamical mechanism in the proton and present notable challenges to the nuclear theory.
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Affiliation(s)
- R Li
- Temple University, Philadelphia, PA, USA
| | | | - H Atac
- Temple University, Philadelphia, PA, USA
| | - M K Jones
- Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
| | - M Paolone
- New Mexico State University, Las Cruces, NM, USA
| | - Z Akbar
- University of Virginia, Charlottesville, VA, USA
| | | | - V Berdnikov
- Catholic University of America, Washington, DC, USA
| | - D Biswas
- Hampton University, Hampton, VA, USA.,Virginia Polytechnic Institute & State University, Blacksburg, VA, USA
| | - M Boer
- Temple University, Philadelphia, PA, USA.,Virginia Polytechnic Institute & State University, Blacksburg, VA, USA
| | - A Camsonne
- Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
| | - J-P Chen
- Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
| | - M Diefenthaler
- Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
| | - B Duran
- Temple University, Philadelphia, PA, USA
| | - D Dutta
- Mississippi State University, Mississippi State, MS, USA
| | - D Gaskell
- Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
| | - O Hansen
- Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
| | | | - N Heinrich
- University of Regina, Regina, Saskatchewan, Canada
| | - W Henry
- Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
| | - T Horn
- Catholic University of America, Washington, DC, USA
| | - G M Huber
- University of Regina, Regina, Saskatchewan, Canada
| | - S Jia
- Temple University, Philadelphia, PA, USA
| | - S Joosten
- Argonne National Laboratory, Lemont, IL, USA
| | - A Karki
- Mississippi State University, Mississippi State, MS, USA
| | - S J D Kay
- University of Regina, Regina, Saskatchewan, Canada
| | - V Kumar
- University of Regina, Regina, Saskatchewan, Canada
| | - X Li
- Duke University, Durham, NC, USA
| | - W B Li
- The College of William and Mary, Williamsburg, VA, USA
| | | | - S Malace
- Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
| | - P Markowitz
- Florida International University, University Park, FL, USA
| | - M McCaughan
- Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
| | - Z-E Meziani
- Argonne National Laboratory, Lemont, IL, USA
| | - H Mkrtchyan
- Artem Alikhanian National Laboratory, Yerevan, Armenia
| | - C Morean
- University of Tennessee, Knoxville, TN, USA
| | - M Muhoza
- Catholic University of America, Washington, DC, USA
| | - A Narayan
- Veer Kunwar Singh University, Arrah, India
| | - B Pasquini
- University of Pavia, Pavia, Italy.,Istituto Nazionale di Fisica Nucleare (INFN), Pavia, Italy
| | - M Rehfuss
- Temple University, Philadelphia, PA, USA
| | - B Sawatzky
- Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
| | - G R Smith
- Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
| | - A Smith
- Duke University, Durham, NC, USA
| | - R Trotta
- Catholic University of America, Washington, DC, USA
| | - C Yero
- Florida International University, University Park, FL, USA
| | - X Zheng
- University of Virginia, Charlottesville, VA, USA
| | - J Zhou
- Duke University, Durham, NC, USA
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3
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Mornacchi E, Martel PP, Abt S, Achenbach P, Adlarson P, Afzal F, Ahmed Z, Annand JRM, Arends HJ, Bashkanov M, Beck R, Biroth M, Borisov N, Braghieri A, Briscoe WJ, Cividini F, Collicott C, Costanza S, Denig A, Dolzhikov AS, Downie EJ, Drexler P, Fegan S, Gardner S, Ghosal D, Glazier DI, Gorodnov I, Gradl W, Günther M, Gurevich D, Heijkenskjöld L, Hornidge D, Huber GM, Käser A, Kashevarov VL, Kay SJD, Korolija M, Krusche B, Lazarev A, Livingston K, Lutterer S, MacGregor IJD, Manley DM, Miskimen R, Mocanu M, Mullen C, Neganov A, Neiser A, Ostrick M, Paudyal D, Pedroni P, Powell A, Rostomyan T, Sokhoyan V, Spieker K, Steffen O, Strakovsky I, Strub T, Thiel M, Thomas A, Usov YA, Wagner S, Watts DP, Werthmüller D, Wettig J, Wolfes M, Zachariou N. Measurement of Compton Scattering at MAMI for the Extraction of the Electric and Magnetic Polarizabilities of the Proton. Phys Rev Lett 2022; 128:132503. [PMID: 35426697 DOI: 10.1103/physrevlett.128.132503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 01/31/2022] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
A precise measurement of the differential cross sections dσ/dΩ and the linearly polarized photon beam asymmetry Σ_{3} for Compton scattering on the proton below pion threshold has been performed with a tagged photon beam and almost 4π detector at the Mainz Microtron. The incident photons were produced by the recently upgraded Glasgow-Mainz photon tagging facility and impinged on a cryogenic liquid hydrogen target, with the scattered photons detected in the Crystal Ball/TAPS setup. Using the highest statistics Compton scattering data ever measured on the proton along with two effective field theories (both covariant baryon and heavy-baryon) and one fixed-t dispersion relation model, constraining the fits with the Baldin sum rule, we have obtained the proton electric and magnetic polarizabilities with unprecedented precision: α_{E1}=10.99±0.16±0.47±0.17±0.34, β_{M1}=3.14±0.21±0.24±0.20±0.35; in units of 10^{-4} fm^{3} where the errors are statistical, systematic, spin polarizability dependent, and model dependent.
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Affiliation(s)
- E Mornacchi
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - P P Martel
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
- Mount Allison University, Sackville, New Brunswick E4L 1E6, Canada
| | - S Abt
- Departement für Physik, Universität Basel, CH-4056 Basel, Switzerland
| | - P Achenbach
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - P Adlarson
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - F Afzal
- Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, D-53115 Bonn, Germany
| | - Z Ahmed
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - J R M Annand
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - H J Arends
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - M Bashkanov
- Department of Physics, University of York, Heslington, York Y010 5DD, United Kingdom
| | - R Beck
- Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, D-53115 Bonn, Germany
| | - M Biroth
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - N Borisov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | | | - W J Briscoe
- The George Washington University, Washington, D.C. 20052-0001, USA
| | - F Cividini
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - C Collicott
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - S Costanza
- INFN Sezione di Pavia, I-27100 Pavia, Italy
| | - A Denig
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - A S Dolzhikov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - E J Downie
- The George Washington University, Washington, D.C. 20052-0001, USA
| | - P Drexler
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - S Fegan
- Department of Physics, University of York, Heslington, York Y010 5DD, United Kingdom
| | - S Gardner
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - D Ghosal
- Departement für Physik, Universität Basel, CH-4056 Basel, Switzerland
| | - D I Glazier
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - I Gorodnov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - W Gradl
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - M Günther
- Departement für Physik, Universität Basel, CH-4056 Basel, Switzerland
| | - D Gurevich
- Institute for Nuclear Research, 125047 Moscow, Russia
| | - L Heijkenskjöld
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - D Hornidge
- Mount Allison University, Sackville, New Brunswick E4L 1E6, Canada
| | - G M Huber
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - A Käser
- Departement für Physik, Universität Basel, CH-4056 Basel, Switzerland
| | - V L Kashevarov
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - S J D Kay
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - M Korolija
- Rudjer Boskovic Institute, HR-10000 Zagreb, Croatia
| | - B Krusche
- Departement für Physik, Universität Basel, CH-4056 Basel, Switzerland
| | - A Lazarev
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - K Livingston
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - S Lutterer
- Departement für Physik, Universität Basel, CH-4056 Basel, Switzerland
| | - I J D MacGregor
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - D M Manley
- Kent State University, Kent, Ohio 44242-0001, USA
| | - R Miskimen
- University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - M Mocanu
- Department of Physics, University of York, Heslington, York Y010 5DD, United Kingdom
| | - C Mullen
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - A Neganov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - A Neiser
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - M Ostrick
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - D Paudyal
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - P Pedroni
- INFN Sezione di Pavia, I-27100 Pavia, Italy
| | - A Powell
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - T Rostomyan
- Departement für Physik, Universität Basel, CH-4056 Basel, Switzerland
| | - V Sokhoyan
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - K Spieker
- Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, D-53115 Bonn, Germany
| | - O Steffen
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - I Strakovsky
- The George Washington University, Washington, D.C. 20052-0001, USA
| | - T Strub
- Departement für Physik, Universität Basel, CH-4056 Basel, Switzerland
| | - M Thiel
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - A Thomas
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - Yu A Usov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - S Wagner
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - D P Watts
- Department of Physics, University of York, Heslington, York Y010 5DD, United Kingdom
| | - D Werthmüller
- Department of Physics, University of York, Heslington, York Y010 5DD, United Kingdom
| | - J Wettig
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - M Wolfes
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
| | - N Zachariou
- Department of Physics, University of York, Heslington, York Y010 5DD, United Kingdom
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Mullen C, Gardner S, Glazier DI, Kay SJD, Livingston K, Strakovsky II, Workman RL, Abt S, Achenbach P, Afzal F, Ahmed Z, Akondi CS, Annand JRM, Bashkanov M, Beck R, Biroth M, Borisov NS, Braghieri A, Briscoe WJ, Cividini F, Collicott C, Costanza S, Denig A, Dieterle M, Downie EJ, Drexler P, Fegan S, Ferretti-Bondy MI, Ghosal D, Gorodnov I, Gradl W, Günther M, Gurevic G, Heijkenskjöld L, Hornidge D, Huber GM, Jermann N, Kaeser A, Korolija M, Kashevarov VL, Krusche B, Kulikov VV, Lazarev A, Lutterer S, MacGregor IJD, Manley DM, Martel PP, Martemianov MA, Meier C, Miskimen R, Mocanu M, Mornacchi E, Neganov A, Oberle M, Ostrick M, Otte P, Paudyal D, Pedroni P, Powell A, Prakhov SN, Reicherz G, Ron G, Rostomyan T, Sfienti C, Sokhoyan V, Spieker K, Steffen O, Strub T, Supek I, Thiel A, Thiel M, Thomas A, Unverzagt M, Usov YA, Wagner S, Walford NK, Watts DP, Werthmüller D, Wettig J, Witthauer L, Wolfes M, Zachariou N. Single π 0 production off neutrons bound in deuteron with linearly polarized photons. Eur Phys J A Hadron Nucl 2021; 57:205. [PMID: 34720708 PMCID: PMC8550430 DOI: 10.1140/epja/s10050-021-00521-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 06/10/2021] [Indexed: 06/13/2023]
Abstract
The quasifree γ → d → π 0 n ( p ) photon beam asymmetry, Σ , has been measured at photon energies, E γ , from 390 to 610 MeV, corresponding to center of mass energy from 1.271 to 1.424 GeV, for the first time. The data were collected in the A2 hall of the MAMI electron beam facility with the Crystal Ball and TAPS calorimeters covering pion center-of-mass angles from 49 ∘ to 148 ∘ . In this kinematic region, polarization observables are sensitive to contributions from the Δ ( 1232 ) and N(1440) resonances. The extracted values of Σ have been compared to predictions based on partial-wave analyses (PWAs) of the existing pion photoproduction database. Our comparison includes the SAID, MAID and Bonn-Gatchina analyses; while a revised SAID fit, including the new Σ measurements, has also been performed. In addition, isospin symmetry is examined as a way to predict π 0 n photoproduction observables, based on fits to published data in the channels π 0 p , π + n and π - p .
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Affiliation(s)
- C. Mullen
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ UK
| | - S. Gardner
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ UK
| | - D. I. Glazier
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ UK
| | - S. J. D. Kay
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD UK
- Department of Physics, University of Regina, Regina, SK S4S 0A2 Canada
| | - K. Livingston
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ UK
| | - I. I. Strakovsky
- Department of Physics, Institute for Nuclear Studies, The George Washington University, Washington, DC, 20052 USA
| | - R. L. Workman
- Department of Physics, Institute for Nuclear Studies, The George Washington University, Washington, DC, 20052 USA
| | - S. Abt
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - P. Achenbach
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - F. Afzal
- Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, 53115 Bonn, Germany
| | - Z. Ahmed
- Department of Physics, University of Regina, Regina, SK S4S 0A2 Canada
| | | | - J. R. M. Annand
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ UK
| | - M. Bashkanov
- Department of Physics, University of York, Heslington, York, Y010 5DD UK
| | - R. Beck
- Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, 53115 Bonn, Germany
| | - M. Biroth
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | | | | | - W. J. Briscoe
- Department of Physics, Institute for Nuclear Studies, The George Washington University, Washington, DC, 20052 USA
| | - F. Cividini
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - C. Collicott
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | | | - A. Denig
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - M. Dieterle
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - E. J. Downie
- Department of Physics, Institute for Nuclear Studies, The George Washington University, Washington, DC, 20052 USA
| | - P. Drexler
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - S. Fegan
- Department of Physics, University of York, Heslington, York, Y010 5DD UK
| | - M. I. Ferretti-Bondy
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - D. Ghosal
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | | | - W. Gradl
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - M. Günther
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - G. Gurevic
- Institute for Nuclear Research, 125047 Moscow, Russia
| | - L. Heijkenskjöld
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - D. Hornidge
- Mount Allison University, Sackville, NB E4L3B5 Canada
| | - G. M. Huber
- Department of Physics, University of Regina, Regina, SK S4S 0A2 Canada
| | - N. Jermann
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - A. Kaeser
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - M. Korolija
- Rudjer Boskovic Institute, 10000 Zagreb, Croatia
| | - V. L. Kashevarov
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
- JINR, 141980 Dubna, Russia
| | - B. Krusche
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - V. V. Kulikov
- NRC “Kurchatov Institute”-ITEP, 117218 Moscow, Russia
| | - A. Lazarev
- Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, 53115 Bonn, Germany
| | - S. Lutterer
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - I. J. D. MacGregor
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ UK
| | | | - P. P. Martel
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | | | - C. Meier
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - R. Miskimen
- University of Massachusetts, Amherst, MA 01003 USA
| | - M. Mocanu
- Department of Physics, University of York, Heslington, York, Y010 5DD UK
| | - E. Mornacchi
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | | | - M. Oberle
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - M. Ostrick
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - P. Otte
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - D. Paudyal
- Department of Physics, University of Regina, Regina, SK S4S 0A2 Canada
| | - P. Pedroni
- INFN Sezione di Pavia, 27100 Pavia, Italy
| | - A. Powell
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ UK
| | - S. N. Prakhov
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - G. Reicherz
- Institut für Experimentalphysik, Ruhr-University of Bochum, 44801 Bochum, Germany
| | - G. Ron
- Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem, Israel
| | - T. Rostomyan
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - C. Sfienti
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - V. Sokhoyan
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - K. Spieker
- Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, 53115 Bonn, Germany
| | - O. Steffen
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - Th. Strub
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - I. Supek
- Rudjer Boskovic Institute, 10000 Zagreb, Croatia
| | - A. Thiel
- Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, 53115 Bonn, Germany
| | - M. Thiel
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - A. Thomas
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - M. Unverzagt
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | | | - S. Wagner
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - N. K. Walford
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - D. P. Watts
- Department of Physics, University of York, Heslington, York, Y010 5DD UK
| | - D. Werthmüller
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ UK
| | - J. Wettig
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - L. Witthauer
- Institut für Physik, University of Basel, 4056 Basel, Switzerland
| | - M. Wolfes
- Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - N. Zachariou
- Department of Physics, University of York, Heslington, York, Y010 5DD UK
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Bashkanov M, Watts DP, Kay SJD, Abt S, Achenbach P, Adlarson P, Afzal F, Ahmed Z, Akondi CS, Annand JRM, Arends HJ, Beck R, Biroth M, Borisov N, Braghieri A, Briscoe WJ, Cividini F, Collicott C, Costanza S, Denig A, Downie EJ, Drexler P, Fegan S, Fix A, Gardner S, Ghosal D, Glazier DI, Gorodnov I, Gradl W, Günther M, Gurevich D, Heijkenskjöld L, Hornidge D, Huber GM, Käser A, Kashevarov VL, Korolija M, Krusche B, Lazarev A, Livingston K, Lutterer S, MacGregor IJD, Manley DM, Martel PP, Miskimen R, Mornacchi E, Mullen C, Neganov A, Neiser A, Ostrick M, Otte PB, Paudyal D, Pedroni P, Powell A, Prakhov SN, Ron G, Sarty A, Sfienti C, Sokhoyan V, Spieker K, Steffen O, Strakovsky II, Strub T, Supek I, Thiel A, Thiel M, Thomas A, Usov YA, Wagner S, Walford NK, Werthmüller D, Wettig J, Wolfes M, Zachariou N, Zana LA. Signatures of the d^{*}(2380) Hexaquark in d(γ,pn[over →]). Phys Rev Lett 2020; 124:132001. [PMID: 32302204 DOI: 10.1103/physrevlett.124.132001] [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: 11/19/2019] [Revised: 01/30/2020] [Accepted: 03/02/2020] [Indexed: 06/11/2023]
Abstract
We report a measurement of the spin polarization of the recoiling neutron in deuterium photodisintegration, utilizing a new large acceptance polarimeter within the Crystal Ball at MAMI. The measured photon energy range of 300-700 MeV provides the first measurement of recoil neutron polarization at photon energies where the quark substructure of the deuteron plays a role, thereby providing important new constraints on photodisintegration mechanisms. A very high neutron polarization in a narrow structure centered around E_{γ}∼570 MeV is observed, which is inconsistent with current theoretical predictions employing nucleon resonance degrees of freedom. A Legendre polynomial decomposition suggests this behavior could be related to the excitation of the d^{*}(2380) hexaquark.
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Affiliation(s)
- M Bashkanov
- Department of Physics, University of York, Heslington, York Y010 5DD, United Kingdom
| | - D P Watts
- Department of Physics, University of York, Heslington, York Y010 5DD, United Kingdom
| | - S J D Kay
- University of Regina, Regina, SK S4S0A2 Canada
| | - S Abt
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - P Achenbach
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - P Adlarson
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - F Afzal
- Helmholtz-Institut für Strahlen- und Kernphysik, University Bonn, D-53115 Bonn, Germany
| | - Z Ahmed
- University of Regina, Regina, SK S4S0A2 Canada
| | - C S Akondi
- Kent State University, Kent, Ohio 44242, USA
| | - J R M Annand
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - H J Arends
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - R Beck
- Helmholtz-Institut für Strahlen- und Kernphysik, University Bonn, D-53115 Bonn, Germany
| | - M Biroth
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - N Borisov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - A Braghieri
- INFN Sezione di Pavia, I-27100 Pavia, Pavia, Italy
| | - W J Briscoe
- Center for Nuclear Studies, The George Washington University, Washington, DC 20052, USA
| | - F Cividini
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - C Collicott
- Department of Astronomy and Physics, Saint Mary's University, E4L1E6 Halifax, Canada
| | - S Costanza
- INFN Sezione di Pavia, I-27100 Pavia, Pavia, Italy
- Dipartimento di Fisica, Università di Pavia, I-27100 Pavia, Italy
| | - A Denig
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - E J Downie
- Center for Nuclear Studies, The George Washington University, Washington, DC 20052, USA
| | - P Drexler
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
- II. Physikalisches Institut, University of Giessen, D-35392 Giessen, Germany
| | - S Fegan
- Department of Physics, University of York, Heslington, York Y010 5DD, United Kingdom
| | - A Fix
- Tomsk Polytechnic University, 634034 Tomsk, Russia
| | - S Gardner
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - D Ghosal
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - D I Glazier
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - I Gorodnov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - W Gradl
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - M Günther
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - D Gurevich
- Institute for Nuclear Research, RU-125047 Moscow, Russia
| | - L Heijkenskjöld
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - D Hornidge
- Mount Allison University, Sackville, New Brunswick E4L1E6, Canada
| | - G M Huber
- University of Regina, Regina, SK S4S0A2 Canada
| | - A Käser
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - V L Kashevarov
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - M Korolija
- Rudjer Boskovic Institute, HR-10000 Zagreb, Croatia
| | - B Krusche
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - A Lazarev
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - K Livingston
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - S Lutterer
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - I J D MacGregor
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - D M Manley
- Kent State University, Kent, Ohio 44242, USA
| | - P P Martel
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
- Mount Allison University, Sackville, New Brunswick E4L1E6, Canada
| | - R Miskimen
- University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - E Mornacchi
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - C Mullen
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - A Neganov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - A Neiser
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - M Ostrick
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - P B Otte
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - D Paudyal
- University of Regina, Regina, SK S4S0A2 Canada
| | - P Pedroni
- INFN Sezione di Pavia, I-27100 Pavia, Pavia, Italy
| | - A Powell
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - S N Prakhov
- University of California Los Angeles, Los Angeles, California 90095-1547, USA
| | - G Ron
- Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - A Sarty
- Department of Astronomy and Physics, Saint Mary's University, E4L1E6 Halifax, Canada
| | - C Sfienti
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - V Sokhoyan
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - K Spieker
- Helmholtz-Institut für Strahlen- und Kernphysik, University Bonn, D-53115 Bonn, Germany
| | - O Steffen
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - I I Strakovsky
- Center for Nuclear Studies, The George Washington University, Washington, DC 20052, USA
| | - T Strub
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - I Supek
- Rudjer Boskovic Institute, HR-10000 Zagreb, Croatia
| | - A Thiel
- Helmholtz-Institut für Strahlen- und Kernphysik, University Bonn, D-53115 Bonn, Germany
| | - M Thiel
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - A Thomas
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - Yu A Usov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - S Wagner
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - N K Walford
- Department of Physics, University of Basel, Ch-4056 Basel, Switzerland
| | - D Werthmüller
- Department of Physics, University of York, Heslington, York Y010 5DD, United Kingdom
| | - J Wettig
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - M Wolfes
- Institut für Kernphysik, University of Mainz, D-55099 Mainz, Germany
| | - N Zachariou
- Department of Physics, University of York, Heslington, York Y010 5DD, United Kingdom
| | - L A Zana
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
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