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Christy ME, Gautam T, Ou L, Schmookler B, Wang Y, Adikaram D, Ahmed Z, Albataineh H, Ali SF, Aljawrneh B, Allada K, Allison SL, Alsalmi S, Androic D, Aniol K, Annand J, Arrington J, Atac H, Averett T, Ayerbe Gayoso C, Bai X, Bane J, Barcus S, Bartlett K, Bellini V, Beminiwattha R, Bericic J, Bhatt H, Bhetuwal D, Biswas D, Brash E, Bulumulla D, Camacho CM, Campbell J, Camsonne A, Carmignotto M, Castellanos J, Chen C, Chen JP, Chetry T, Cisbani E, Clary B, Cohen E, Compton N, Cornejo JC, Covrig Dusa S, Crowe B, Danagoulian S, Danley T, Deconinck W, Defurne M, Desnault C, Di D, Dlamini M, Duer M, Duran B, Ent R, Fanelli C, Fuchey E, Gal C, Gaskell D, Georges F, Gilad S, Glamazdin O, Gnanvo K, Gramolin AV, Gray VM, Gu C, Habarakada A, Hague T, Hamad G, Hamilton D, Hamilton K, Hansen O, Hauenstein F, Hernandez AV, Henry W, Higinbotham DW, Holmstrom T, Horn T, Huang Y, Huber GM, Hyde C, Ibrahim H, Israel N, Jen CM, Jin K, Jones M, Kabir A, Karki B, Keppel C, Khachatryan V, King PM, Li S, Li W, Liu H, Liu J, Liyanage AH, Mack D, Magee J, Malace S, Mammei J, Markowitz P, Mayilyan S, McClellan E, Meddi F, Meekins D, Mesick K, Michaels R, Mkrtchyan A, Moffit B, Montgomery R, Myers LS, Nadel-Turonski P, Nazeer SJ, Nelyubin V, Nguyen D, Nuruzzaman N, Nycz M, Obrecht RF, Ohanyan K, Palatchi C, Pandey B, Park K, Park S, Peng C, Persio FD, Pomatsalyuk R, Pooser E, Puckett AJR, Punjabi V, Quinn B, Rahman S, Rashad MNH, Reimer PE, Riordan S, Roche J, Sapkota I, Sarty A, Sawatzky B, Saylor NH, Shabestari MH, Shahinyan A, Širca S, Smith GR, Sooriyaarachchilage S, Sparveris N, Spies R, Stefanko A, Su T, Subedi A, Sulkosky V, Sun A, Tan Y, Thorne L, Ton N, Tortorici F, Trotta R, Uniyal R, Urciuoli GM, Voutier E, Waidyawansa B, Wojtsekhowski B, Wood S, Yan X, Ye L, Ye ZH, Yero C, Zhang J, Zhao YX, Zhu P. Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering. PHYSICAL REVIEW LETTERS 2022; 128:102002. [PMID: 35333083 DOI: 10.1103/physrevlett.128.102002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 11/06/2021] [Accepted: 01/31/2022] [Indexed: 06/14/2023]
Abstract
We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q^{2}) up to 15.75 (GeV/c)^{2}. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q^{2} and double the range over which a longitudinal or transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q^{2} and attributed to hard two-photon exchange (TPE) effects, extending to 8 (GeV/c)^{2} the range of Q^{2} for which a discrepancy is established at >95% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q^{2}.
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Affiliation(s)
- M E Christy
- Hampton University, Hampton, Virginia 23669, USA
| | - T Gautam
- Hampton University, Hampton, Virginia 23669, USA
| | - L Ou
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - B Schmookler
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Y Wang
- William and Mary, Williamsburg, Virginia 23185, USA
| | - D Adikaram
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - Z Ahmed
- University of Regina, Regina, Saskatchewan S4S 0A2 Canada
| | - H Albataineh
- Texas A & M University, Kingsville, Texas 77843, USA
| | - S F Ali
- Catholic University of America, Washington, District of Columbia 20064, USA
| | - B Aljawrneh
- North Carolina A&T State University, Greensboro, North Carolina 27411, USA
- Al Zaytoonah University of Jordan, Amman 11733, Jordan
| | - K Allada
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - S L Allison
- Old Dominion University, Norfolk, Virginia 23529, USA
| | - S Alsalmi
- Kent State University, Kent, Ohio 44240, USA
| | - D Androic
- University of Zagreb, Trg Republike Hrvatske 14, 10000, Zagreb, Croatia
| | - K Aniol
- California State University, Los Angeles, Los Angeles, California 90032, USA
| | - J Annand
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - J Arrington
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - H Atac
- Temple University, Philadelphia, Pennsylvania 19122, USA
| | - T Averett
- William and Mary, Williamsburg, Virginia 23185, USA
| | | | - X Bai
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - J Bane
- University of Tennessee, Knoxville, Tennessee 37996, USA
| | - S Barcus
- William and Mary, Williamsburg, Virginia 23185, USA
| | - K Bartlett
- William and Mary, Williamsburg, Virginia 23185, USA
| | - V Bellini
- Istituto Nazionale di Fisica Nucleare, Department of Physics and Astronomy, I-95123 Catania, Italy
| | | | - J Bericic
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - H Bhatt
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - D Bhetuwal
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - D Biswas
- Hampton University, Hampton, Virginia 23669, USA
| | - E Brash
- Christopher Newport University, Newport News, Virginia 23606, USA
| | - D Bulumulla
- Old Dominion University, Norfolk, Virginia 23529, USA
| | - C M Camacho
- Institut de Physique Nucleaire, 15 Rue Georges Clemenceau, 91400 Orsay, France
| | - J Campbell
- Dalhousie University, Nova Scotia NS B3H 4R2, Canada
| | - A Camsonne
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - M Carmignotto
- Catholic University of America, Washington, DC 20064, USA
| | - J Castellanos
- Florida International University, Miami, Florida 33199, USA
| | - C Chen
- Hampton University, Hampton, Virginia 23669, USA
| | - J-P Chen
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - T Chetry
- Ohio University, Athens, Ohio 45701, USA
| | - E Cisbani
- Istituto Nazionale di Fisica Nucleare - Sezione di Roma, P.le Aldo Moro, 2 - 00185 Roma, Italy
| | - B Clary
- University of Connecticut, Storrs, Connecticut 06269, USA
| | - E Cohen
- Tel Aviv University, Tel Aviv-Yafo 69978, Israel
| | - N Compton
- Ohio University, Athens, Ohio 45701, USA
| | - J C Cornejo
- William and Mary, Williamsburg, Virginia 23185, USA
- Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - S Covrig Dusa
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - B Crowe
- North Carolina Central University, Durham, North Carolina 27707, USA
| | - S Danagoulian
- North Carolina A&T State University, Greensboro, North Carolina 27411, USA
| | - T Danley
- Ohio University, Athens, Ohio 45701, USA
| | - W Deconinck
- William and Mary, Williamsburg, Virginia 23185, USA
| | - M Defurne
- CEA Saclay, 91191 Gif-sur-Yvette, France
| | - C Desnault
- Institut de Physique Nucleaire, 15 Rue Georges Clemenceau, 91400 Orsay, France
| | - D Di
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - M Dlamini
- Ohio University, Athens, Ohio 45701, USA
| | - M Duer
- Tel Aviv University, Tel Aviv-Yafo 69978, Israel
| | - B Duran
- Temple University, Philadelphia, Pennsylvania 19122, USA
| | - R Ent
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - C Fanelli
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - E Fuchey
- University of Connecticut, Storrs, Connecticut 06269, USA
| | - C Gal
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - D Gaskell
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - F Georges
- Ecole Centrale Paris, 3 Rue Joliot Curie, 91190 Gif-sur-Yvette, France
| | - S Gilad
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - O Glamazdin
- Kharkov Institute of Physics and Technology, Kharkov 61108, Ukraine
| | - K Gnanvo
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - A V Gramolin
- Boston University, Boston, Massachusetts 02215, USA
| | - V M Gray
- William and Mary, Williamsburg, Virginia 23185, USA
| | - C Gu
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - A Habarakada
- Hampton University, Hampton, Virginia 23669, USA
| | - T Hague
- Kent State University, Kent, Ohio 44240, USA
| | - G Hamad
- Ohio University, Athens, Ohio 45701, USA
| | - D Hamilton
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - K Hamilton
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - O Hansen
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - F Hauenstein
- Old Dominion University, Norfolk, Virginia 23529, USA
| | - A V Hernandez
- Catholic University of America, Washington, DC 20064, USA
| | - W Henry
- Temple University, Philadelphia, Pennsylvania 19122, USA
| | - D W Higinbotham
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - T Holmstrom
- Randolph Macon College, Ashland, Virginia 23005, USA
| | - T Horn
- Catholic University of America, Washington, DC 20064, USA
| | - Y Huang
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - G M Huber
- University of Regina, Regina, Saskatchewan S4S 0A2 Canada
| | - C Hyde
- Old Dominion University, Norfolk, Virginia 23529, USA
| | - H Ibrahim
- Cairo University, Cairo, 12613, Egypt
| | - N Israel
- Ohio University, Athens, Ohio 45701, USA
| | - C-M Jen
- Virginia Polytechnic Institute and State University, Blacksburg, Virginia 234061, USA
| | - K Jin
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - M Jones
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - A Kabir
- Kent State University, Kent, Ohio 44240, USA
| | - B Karki
- Ohio University, Athens, Ohio 45701, USA
| | - C Keppel
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - V Khachatryan
- Stony Brook, State University of New York, New York 11794, USA
- Cornell University, Ithaca, New York 14853, USA
| | - P M King
- Ohio University, Athens, Ohio 45701, USA
| | - S Li
- University of New Hampshire, Durham, New Hampshire 03824, USA
| | - W Li
- University of Regina, Regina, Saskatchewan S4S 0A2 Canada
| | - H Liu
- Columbia University, New York, New York 10027, USA
| | - J Liu
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - A H Liyanage
- Hampton University, Hampton, Virginia 23669, USA
| | - D Mack
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - J Magee
- William and Mary, Williamsburg, Virginia 23185, USA
| | - S Malace
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - J Mammei
- University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - P Markowitz
- Florida International University, Miami, Florida 33199, USA
| | - S Mayilyan
- AANL, 2 Alikhanian Brothers Street, 0036 Yerevan, Armenia
| | - E McClellan
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - F Meddi
- Istituto Nazionale di Fisica Nucleare - Sezione di Roma, P.le Aldo Moro, 2 - 00185 Roma, Italy
| | - D Meekins
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - K Mesick
- Rutgers University, New Brunswick, New Jersey 08854, USA
| | - R Michaels
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - A Mkrtchyan
- Catholic University of America, Washington, DC 20064, USA
| | - B Moffit
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - R Montgomery
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - L S Myers
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - P Nadel-Turonski
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - S J Nazeer
- Hampton University, Hampton, Virginia 23669, USA
| | - V Nelyubin
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - D Nguyen
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - N Nuruzzaman
- Hampton University, Hampton, Virginia 23669, USA
| | - M Nycz
- Kent State University, Kent, Ohio 44240, USA
| | - R F Obrecht
- University of Connecticut, Storrs, Connecticut 06269, USA
| | - K Ohanyan
- AANL, 2 Alikhanian Brothers Street, 0036 Yerevan, Armenia
| | - C Palatchi
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - B Pandey
- Hampton University, Hampton, Virginia 23669, USA
| | - K Park
- Old Dominion University, Norfolk, Virginia 23529, USA
| | - S Park
- Stony Brook, State University of New York, New York 11794, USA
| | - C Peng
- Duke University, Durham, North Carolina 27708, USA
| | - F D Persio
- Istituto Nazionale di Fisica Nucleare - Sezione di Roma, P.le Aldo Moro, 2 - 00185 Roma, Italy
| | - R Pomatsalyuk
- Kharkov Institute of Physics and Technology, Kharkov 61108, Ukraine
| | - E Pooser
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - A J R Puckett
- University of Connecticut, Storrs, Connecticut 06269, USA
| | - V Punjabi
- Norfolk State University, Norfolk, Virginia 23504, USA
| | - B Quinn
- Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - S Rahman
- University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - M N H Rashad
- Old Dominion University, Norfolk, Virginia 23529, USA
| | - P E Reimer
- Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - S Riordan
- Stony Brook, State University of New York, New York 11794, USA
| | - J Roche
- Ohio University, Athens, Ohio 45701, USA
| | - I Sapkota
- Catholic University of America, Washington, DC 20064, USA
| | - A Sarty
- Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada
| | - B Sawatzky
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - N H Saylor
- Rensselaer Polytechnic Institute, Troy, New York 12180, USA
| | - M H Shabestari
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - A Shahinyan
- AANL, 2 Alikhanian Brothers Street, 0036 Yerevan, Armenia
| | - S Širca
- Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - G R Smith
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | | | - N Sparveris
- Temple University, Philadelphia, Pennsylvania 19122, USA
| | - R Spies
- University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - A Stefanko
- Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - T Su
- Kent State University, Kent, Ohio 44240, USA
| | - A Subedi
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - V Sulkosky
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - A Sun
- Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Y Tan
- Shandong University, Shandong, Jinan 250100, China
| | - L Thorne
- Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - N Ton
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - F Tortorici
- Istituto Nazionale di Fisica Nucleare, Department of Physics and Astronomy, I-95123 Catania, Italy
| | - R Trotta
- Duquesne University, Pittsburgh, Pennsylvania 15282, USA
| | - R Uniyal
- Catholic University of America, Washington, DC 20064, USA
| | - G M Urciuoli
- Istituto Nazionale di Fisica Nucleare - Sezione di Roma, P.le Aldo Moro, 2 - 00185 Roma, Italy
| | - E Voutier
- Institut de Physique Nucleaire, 15 Rue Georges Clemenceau, 91400 Orsay, France
| | - B Waidyawansa
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - B Wojtsekhowski
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - S Wood
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - X Yan
- Huangshan University, 44 Daizhen Road, Tunxi District, Huangshan, Anhui Province, China
| | - L Ye
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - Z H Ye
- University of Virginia, Charlottesville, Virginia 232904, USA
- Tsinghua University, 30 Shuangqing Rd, Haidian District, Beijing 100190, China
| | - C Yero
- Florida International University, Miami, Florida 33199, USA
| | - J Zhang
- University of Virginia, Charlottesville, Virginia 232904, USA
| | - Y X Zhao
- Stony Brook, State University of New York, New York 11794, USA
| | - P Zhu
- University of Science and Technology of China, Hefei, Anhui 230026, China
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Tiesinga E, Mohr PJ, Newell DB, Taylor BN. CODATA Recommended Values of the Fundamental Physical Constants: 2018. JOURNAL OF PHYSICAL AND CHEMICAL REFERENCE DATA 2021; 50:033105. [PMID: 36726646 PMCID: PMC9888147 DOI: 10.1063/5.0064853] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 02/02/2021] [Indexed: 05/19/2023]
Abstract
We report the 2018 self-consistent values of constants and conversion factors of physics and chemistry recommended by the Committee on Data of the International Science Council. The recommended values can also be found at physics.nist.gov/constants. The values are based on a least-squares adjustment that takes into account all theoretical and experimental data available through 31 December 2018. A discussion of the major improvements as well as inconsistencies within the data is given. The former include a decrease in the uncertainty of the dimensionless fine-structure constant and a nearly two orders of magnitude improvement of particle masses expressed in units of kg due to the transition to the revised International System of Units (SI) with an exact value for the Planck constant. Further, because the elementary charge, Boltzmann constant, and Avogadro constant also have exact values in the revised SI, many other constants are either exact or have significantly reduced uncertainties. Inconsistencies remain for the gravitational constant and the muon magnetic-moment anomaly. The proton charge radius puzzle has been partially resolved by improved measurements of hydrogen energy levels.
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Tiesinga E, Mohr PJ, Newell DB, Taylor BN. CODATA recommended values of the fundamental physical constants: 2018. REVIEWS OF MODERN PHYSICS 2021; 93:025010. [PMID: 36733295 PMCID: PMC9890581 DOI: 10.1103/revmodphys.93.025010] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We report the 2018 self-consistent values of constants and conversion factors of physics and chemistry recommended by the Committee on Data of the International Science Council (CODATA). The recommended values can also be found at physics.nist.gov/constants. The values are based on a least-squares adjustment that takes into account all theoretical and experimental data available through 31 December 2018. A discussion of the major improvements as well as inconsistencies within the data is given. The former include a decrease in the uncertainty of the dimensionless fine-structure constant and a nearly two orders of magnitude improvement of particle masses expressed in units of kg due to the transition to the revised International System of Units (SI) with an exact value for the Planck constant. Further, because the elementary charge, Boltzmann constant, and Avogadro constant also have exact values in the revised SI, many other constants are either exact or have significantly reduced uncertainties. Inconsistencies remain for the gravitational constant and the muon magnetic-moment anomaly. The proton charge radius puzzle has been partially resolved by improved measurements of hydrogen energy levels.
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Affiliation(s)
- Eite Tiesinga
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, College Park, Maryland 20742, USA
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Peter J. Mohr
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - David B. Newell
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Barry N. Taylor
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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Androić D, Armstrong DS, Asaturyan A, Bartlett K, Beaufait J, Beminiwattha RS, Benesch J, Benmokhtar F, Birchall J, Carlini RD, Cornejo JC, Dusa SC, Dalton MM, Davis CA, Deconinck W, Dowd JF, Dunne JA, Dutta D, Duvall WS, Elaasar M, Falk WR, Finn JM, Forest T, Gal C, Gaskell D, Gericke MTW, Grames J, Gray VM, Grimm K, Guo F, Hoskins JR, Jones D, Jones MK, Jones RT, Kargiantoulakis M, King PM, Korkmaz E, Kowalski S, Leacock J, Leckey JP, Lee AR, Lee JH, Lee L, MacEwan S, Mack D, Magee JA, Mahurin R, Mammei J, Martin JW, McHugh MJ, Meekins D, Mei J, Mesick KE, Michaels R, Micherdzinska A, Mkrtchyan A, Mkrtchyan H, Morgan N, Narayan A, Ndukum LZ, Nelyubin V, van Oers WTH, Owen VF, Page SA, Pan J, Paschke KD, Phillips SK, Pitt ML, Radloff RW, Rajotte JF, Ramsay WD, Roche J, Sawatzky B, Seva T, Shabestari MH, Silwal R, Simicevic N, Smith GR, Solvignon P, Spayde DT, Subedi A, Subedi R, Suleiman R, Tadevosyan V, Tobias WA, Tvaskis V, Waidyawansa B, Wang P, Wells SP, Wood SA, Yang S, Zang P, Zhamkochyan S. Precision Measurement of the Beam-Normal Single-Spin Asymmetry in Forward-Angle Elastic Electron-Proton Scattering. PHYSICAL REVIEW LETTERS 2020; 125:112502. [PMID: 32976004 DOI: 10.1103/physrevlett.125.112502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 08/07/2020] [Accepted: 08/11/2020] [Indexed: 06/11/2023]
Abstract
A beam-normal single-spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable related to the imaginary part of the two-photon exchange process. We report a 2% precision measurement of the beam-normal single-spin asymmetry in elastic electron-proton scattering with a mean scattering angle of θ_{lab}=7.9° and a mean energy of 1.149 GeV. The asymmetry result is B_{n}=-5.194±0.067(stat)±0.082 (syst) ppm. This is the most precise measurement of this quantity available to date and therefore provides a stringent test of two-photon exchange models at far-forward scattering angles (θ_{lab}→0) where they should be most reliable.
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Affiliation(s)
- D Androić
- University of Zagreb, Zagreb, HR 10002, Croatia
| | | | - A Asaturyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| | - K Bartlett
- William & Mary, Williamsburg, Virginia 23185, USA
| | - J Beaufait
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - R S Beminiwattha
- Ohio University, Athens, Ohio 45701, USA
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - J Benesch
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - F Benmokhtar
- Duquesne University, Pittburgh, Pennsylvania 15282, USA
| | - J Birchall
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - R D Carlini
- William & Mary, Williamsburg, Virginia 23185, USA
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - J C Cornejo
- William & Mary, Williamsburg, Virginia 23185, USA
| | - S Covrig Dusa
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - M M Dalton
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - C A Davis
- TRIUMF, Vancouver, British Columbia V6T2A3, Canada
| | - W Deconinck
- William & Mary, Williamsburg, Virginia 23185, USA
| | - J F Dowd
- William & Mary, Williamsburg, Virginia 23185, USA
| | - J A Dunne
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - D Dutta
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - W S Duvall
- Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA
| | - M Elaasar
- Southern University at New Orleans, New Orleans, Louisiana 70126, USA
| | - W R Falk
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - J M Finn
- William & Mary, Williamsburg, Virginia 23185, USA
| | - T Forest
- Louisiana Tech University, Ruston, Louisiana 71272, USA
- Idaho State University, Pocatello, Idaho 83209, USA
| | - C Gal
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - D Gaskell
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - M T W Gericke
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - J Grames
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - V M Gray
- William & Mary, Williamsburg, Virginia 23185, USA
| | - K Grimm
- William & Mary, Williamsburg, Virginia 23185, USA
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - F Guo
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - J R Hoskins
- William & Mary, Williamsburg, Virginia 23185, USA
| | - D Jones
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - M K Jones
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - R T Jones
- University of Connecticut, Storrs-Mansfield, Connecticut 06269, USA
| | | | - P M King
- Ohio University, Athens, Ohio 45701, USA
| | - E Korkmaz
- University of Northern British Columbia, Prince George, British Columbia V2N4Z9, Canada
| | - S Kowalski
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - J Leacock
- Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA
| | - J P Leckey
- William & Mary, Williamsburg, Virginia 23185, USA
| | - A R Lee
- Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA
| | - J H Lee
- William & Mary, Williamsburg, Virginia 23185, USA
- Ohio University, Athens, Ohio 45701, USA
| | - L Lee
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- TRIUMF, Vancouver, British Columbia V6T2A3, Canada
| | - S MacEwan
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - D Mack
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - J A Magee
- William & Mary, Williamsburg, Virginia 23185, USA
| | - R Mahurin
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - J Mammei
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA
| | - J W Martin
- University of Winnipeg, Winnipeg, Manitoba R3B2E9, Canada
| | - M J McHugh
- George Washington University, Washington, DC 20052, USA
| | - D Meekins
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - J Mei
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - K E Mesick
- George Washington University, Washington, DC 20052, USA
- Rutgers, The State University of New Jersey, Piscataway, New Jersey 088754, USA
| | - R Michaels
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | | | - A Mkrtchyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| | - H Mkrtchyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| | - N Morgan
- Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA
| | - A Narayan
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - L Z Ndukum
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - V Nelyubin
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - W T H van Oers
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- TRIUMF, Vancouver, British Columbia V6T2A3, Canada
| | - V F Owen
- William & Mary, Williamsburg, Virginia 23185, USA
| | - S A Page
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - J Pan
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - K D Paschke
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - S K Phillips
- University of New Hampshire, Durham, New Hampshire 03824, USA
| | - M L Pitt
- Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA
| | | | - J F Rajotte
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - W D Ramsay
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- TRIUMF, Vancouver, British Columbia V6T2A3, Canada
| | - J Roche
- Ohio University, Athens, Ohio 45701, USA
| | - B Sawatzky
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - T Seva
- University of Zagreb, Zagreb, HR 10002, Croatia
| | - M H Shabestari
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - R Silwal
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - N Simicevic
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - G R Smith
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - P Solvignon
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - D T Spayde
- Hendrix College, Conway, Arkansas 72032, USA
| | - A Subedi
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - R Subedi
- George Washington University, Washington, DC 20052, USA
| | - R Suleiman
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - V Tadevosyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| | - W A Tobias
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - V Tvaskis
- University of Winnipeg, Winnipeg, Manitoba R3B2E9, Canada
| | - B Waidyawansa
- Ohio University, Athens, Ohio 45701, USA
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - P Wang
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - S P Wells
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - S A Wood
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - S Yang
- William & Mary, Williamsburg, Virginia 23185, USA
| | - P Zang
- Syracuse University, Syracuse, New York 13244, USA
| | - S Zhamkochyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
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5
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Gou B, Arvieux J, Aulenbacher K, Ríos DB, Baunack S, Becker D, Capozza L, Deconinck W, Diefenbach J, Frascaria R, Gorchtein M, Gläser B, von Harrach D, Imai Y, Kabuß EM, Kothe R, Kowalski S, Kunne R, Maas FE, Merkel H, Espí MCM, Morlet M, Müller U, Ong S, Schilling E, Weinrich C, van de Wiele J, Zambrana M, Zimmermann I. Study of Two-Photon Exchange via the Beam Transverse Single Spin Asymmetry in Electron-Proton Elastic Scattering at Forward Angles over a Wide Energy Range. PHYSICAL REVIEW LETTERS 2020; 124:122003. [PMID: 32281834 DOI: 10.1103/physrevlett.124.122003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 02/28/2020] [Accepted: 02/28/2020] [Indexed: 06/11/2023]
Abstract
We report on a new measurement of the beam transverse single spin asymmetry in electron-proton elastic scattering, A_{⊥}^{ep}, at five beam energies from 315.1 to 1508.4 MeV and at a scattering angle of 30°<θ<40°. The covered Q^{2} values are 0.032, 0.057, 0.082, 0.218, 0.613 (GeV/c)^{2}. The measurement clearly indicates significant inelastic contributions to the two-photon-exchange (TPE) amplitude in the low-Q^{2} kinematic region. No theoretical calculation is able to reproduce our result. Comparison with a calculation based on unitarity, which only takes into account elastic and πN inelastic intermediate states, suggests that there are other inelastic intermediate states such as ππN, KΛ, and ηN. Covering a wide energy range, our new high-precision data provide a benchmark to study those intermediate states.
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Affiliation(s)
- B Gou
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, Staudingerweg 18, D-55099 Mainz, Germany
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | - J Arvieux
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - K Aulenbacher
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, Staudingerweg 18, D-55099 Mainz, Germany
| | - D Balaguer Ríos
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - S Baunack
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - D Becker
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - L Capozza
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, Staudingerweg 18, D-55099 Mainz, Germany
| | - W Deconinck
- Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - J Diefenbach
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - R Frascaria
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - M Gorchtein
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - B Gläser
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - D von Harrach
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - Y Imai
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - E-M Kabuß
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - R Kothe
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - S Kowalski
- Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - R Kunne
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - F E Maas
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, Staudingerweg 18, D-55099 Mainz, Germany
| | - H Merkel
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - M C Mora Espí
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - M Morlet
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - U Müller
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - S Ong
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - E Schilling
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - C Weinrich
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - J van de Wiele
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - M Zambrana
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, Staudingerweg 18, D-55099 Mainz, Germany
| | - I Zimmermann
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, Staudingerweg 18, D-55099 Mainz, Germany
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6
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Gilfoyle G. Future Measurements of the Nucleon Elastic Electromagnetic Form Factors at Jefferson Lab. EPJ WEB OF CONFERENCES 2018. [DOI: 10.1051/epjconf/201817202004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The elastic, electromagnetic form factors are fundamental observables that describe the internal structure of protons, neutrons, and atomic nuclei. Jefferson Lab in the United States has completed the 12 GeV Upgrade that will open new opportunities to study the form factors. A campaign to measure all four nucleon form factors (electric and magnetic ones for both proton and neutron) has been approved consisting of seven experiments in Halls A, B, and C. The increased energy of the electron beam will extend the range of precision measurements to higher Q2 for all four form factors together. This combination of measurements will allow for the decomposition of the results into their quark components and guide the development of a QCD-based understanding of nuclei in the non-perturbative regime. I will present more details on the 12 GeV Upgrade, the methods used to measure the form factors, and what we may learn.
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7
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Henderson BS, Ice LD, Khaneft D, O'Connor C, Russell R, Schmidt A, Bernauer JC, Kohl M, Akopov N, Alarcon R, Ates O, Avetisyan A, Beck R, Belostotski S, Bessuille J, Brinker F, Calarco JR, Carassiti V, Cisbani E, Ciullo G, Contalbrigo M, De Leo R, Diefenbach J, Donnelly TW, Dow K, Elbakian G, Eversheim PD, Frullani S, Funke C, Gavrilov G, Gläser B, Görrissen N, Hasell DK, Hauschildt J, Hoffmeister P, Holler Y, Ihloff E, Izotov A, Kaiser R, Karyan G, Kelsey J, Kiselev A, Klassen P, Krivshich A, Lehmann I, Lenisa P, Lenz D, Lumsden S, Ma Y, Maas F, Marukyan H, Miklukho O, Milner RG, Movsisyan A, Murray M, Naryshkin Y, Perez Benito R, Perrino R, Redwine RP, Rodríguez Piñeiro D, Rosner G, Schneekloth U, Seitz B, Statera M, Thiel A, Vardanyan H, Veretennikov D, Vidal C, Winnebeck A, Yeganov V. Hard Two-Photon Contribution to Elastic Lepton-Proton Scattering Determined by the OLYMPUS Experiment. PHYSICAL REVIEW LETTERS 2017; 118:092501. [PMID: 28306315 DOI: 10.1103/physrevlett.118.092501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Indexed: 06/06/2023]
Abstract
The OLYMPUS Collaboration reports on a precision measurement of the positron-proton to electron-proton elastic cross section ratio, R_{2γ}, a direct measure of the contribution of hard two-photon exchange to the elastic cross section. In the OLYMPUS measurement, 2.01 GeV electron and positron beams were directed through a hydrogen gas target internal to the DORIS storage ring at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight scintillators detected elastically scattered leptons in coincidence with recoiling protons over a scattering angle range of ≈20° to 80°. The relative luminosity between the two beam species was monitored using tracking telescopes of interleaved gas electron multiplier and multiwire proportional chamber detectors at 12°, as well as symmetric Møller or Bhabha calorimeters at 1.29°. A total integrated luminosity of 4.5 fb^{-1} was collected. In the extraction of R_{2γ}, radiative effects were taken into account using a Monte Carlo generator to simulate the convolutions of internal bremsstrahlung with experiment-specific conditions such as detector acceptance and reconstruction efficiency. The resulting values of R_{2γ}, presented here for a wide range of virtual photon polarization 0.456<ε<0.978, are smaller than some hadronic two-photon exchange calculations predict, but are in reasonable agreement with a subtracted dispersion model and a phenomenological fit to the form factor data.
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Affiliation(s)
- B S Henderson
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - L D Ice
- Arizona State University, Tempe, Arizona 85281, USA
| | - D Khaneft
- Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - C O'Connor
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - R Russell
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - A Schmidt
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - J C Bernauer
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - M Kohl
- Hampton University, Hampton, Virginia 23668, USA
| | - N Akopov
- Alikhanyan National Science Laboratory (Yerevan Physics Institute), 0036 Yerevan, Armenia
| | - R Alarcon
- Arizona State University, Tempe, Arizona 85281, USA
| | - O Ates
- Hampton University, Hampton, Virginia 23668, USA
| | - A Avetisyan
- Alikhanyan National Science Laboratory (Yerevan Physics Institute), 0036 Yerevan, Armenia
| | - R Beck
- Rheinische Friedrich-Wilhelms-Universität, 53113 Bonn, Germany
| | - S Belostotski
- Petersburg Nuclear Physics Institute, Gatchina 188300, Russia
| | - J Bessuille
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - F Brinker
- Deutsches Elektronen-Synchrotron, 22603 Hamburg, Germany
| | - J R Calarco
- University of New Hampshire, Durham, New Hampshire 03824, USA
| | - V Carassiti
- Università degli Studi di Ferrara and Istituto Nazionale di Fisica Nucleare sezione di Ferrara, 44122 Ferrara, Italy
| | - E Cisbani
- Istituto Nazionale di Fisica Nucleare sezione di Roma and Istituto Superiore di Sanità, 00185 Rome, Italy
| | - G Ciullo
- Università degli Studi di Ferrara and Istituto Nazionale di Fisica Nucleare sezione di Ferrara, 44122 Ferrara, Italy
| | - M Contalbrigo
- Università degli Studi di Ferrara and Istituto Nazionale di Fisica Nucleare sezione di Ferrara, 44122 Ferrara, Italy
| | - R De Leo
- Istituto Nazionale di Fisica Nucleare sezione di Bari, 70126 Bari, Italy
| | - J Diefenbach
- Hampton University, Hampton, Virginia 23668, USA
| | - T W Donnelly
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - K Dow
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - G Elbakian
- Alikhanyan National Science Laboratory (Yerevan Physics Institute), 0036 Yerevan, Armenia
| | - P D Eversheim
- Rheinische Friedrich-Wilhelms-Universität, 53113 Bonn, Germany
| | - S Frullani
- Istituto Nazionale di Fisica Nucleare sezione di Roma and Istituto Superiore di Sanità, 00185 Rome, Italy
| | - Ch Funke
- Rheinische Friedrich-Wilhelms-Universität, 53113 Bonn, Germany
| | - G Gavrilov
- Petersburg Nuclear Physics Institute, Gatchina 188300, Russia
| | - B Gläser
- Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - N Görrissen
- Deutsches Elektronen-Synchrotron, 22603 Hamburg, Germany
| | - D K Hasell
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - J Hauschildt
- Deutsches Elektronen-Synchrotron, 22603 Hamburg, Germany
| | - Ph Hoffmeister
- Rheinische Friedrich-Wilhelms-Universität, 53113 Bonn, Germany
| | - Y Holler
- Deutsches Elektronen-Synchrotron, 22603 Hamburg, Germany
| | - E Ihloff
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - A Izotov
- Petersburg Nuclear Physics Institute, Gatchina 188300, Russia
| | - R Kaiser
- University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - G Karyan
- Deutsches Elektronen-Synchrotron, 22603 Hamburg, Germany
| | - J Kelsey
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - A Kiselev
- Petersburg Nuclear Physics Institute, Gatchina 188300, Russia
| | - P Klassen
- Rheinische Friedrich-Wilhelms-Universität, 53113 Bonn, Germany
| | - A Krivshich
- Petersburg Nuclear Physics Institute, Gatchina 188300, Russia
| | - I Lehmann
- University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - P Lenisa
- Università degli Studi di Ferrara and Istituto Nazionale di Fisica Nucleare sezione di Ferrara, 44122 Ferrara, Italy
| | - D Lenz
- Deutsches Elektronen-Synchrotron, 22603 Hamburg, Germany
| | - S Lumsden
- University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Y Ma
- Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - F Maas
- Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - H Marukyan
- Alikhanyan National Science Laboratory (Yerevan Physics Institute), 0036 Yerevan, Armenia
| | - O Miklukho
- Petersburg Nuclear Physics Institute, Gatchina 188300, Russia
| | - R G Milner
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - A Movsisyan
- Alikhanyan National Science Laboratory (Yerevan Physics Institute), 0036 Yerevan, Armenia
| | - M Murray
- University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Y Naryshkin
- Petersburg Nuclear Physics Institute, Gatchina 188300, Russia
| | | | - R Perrino
- Istituto Nazionale di Fisica Nucleare sezione di Bari, 70126 Bari, Italy
| | - R P Redwine
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | | | - G Rosner
- University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - U Schneekloth
- Deutsches Elektronen-Synchrotron, 22603 Hamburg, Germany
| | - B Seitz
- University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - M Statera
- Università degli Studi di Ferrara and Istituto Nazionale di Fisica Nucleare sezione di Ferrara, 44122 Ferrara, Italy
| | - A Thiel
- Rheinische Friedrich-Wilhelms-Universität, 53113 Bonn, Germany
| | - H Vardanyan
- Alikhanyan National Science Laboratory (Yerevan Physics Institute), 0036 Yerevan, Armenia
| | - D Veretennikov
- Petersburg Nuclear Physics Institute, Gatchina 188300, Russia
| | - C Vidal
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - A Winnebeck
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - V Yeganov
- Alikhanyan National Science Laboratory (Yerevan Physics Institute), 0036 Yerevan, Armenia
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