1
|
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. Phys Rev Lett 2020; 124:122003. [PMID: 32281834 DOI: 10.1103/physrevlett.124.122003] [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: 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.
Collapse
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
| |
Collapse
|
2
|
Ríos DB, Aulenbacher K, Baunack S, Diefenbach J, Gläser B, von Harrach D, Imai Y, Kabuß EM, Kothe R, Lee JH, Merkel H, Mora Espí MC, Müller U, Schilling E, Weinrich C, Capozza L, Maas FE, Arvieux J, El-Yakoubi MA, Frascaria R, Kunne R, Morlet M, Ong S, van de Wiele J, Kowalski S, Prok Y. New Measurements of the Beam Normal Spin Asymmetries at Large Backward Angles with Hydrogen and Deuterium Targets. Phys Rev Lett 2017; 119:012501. [PMID: 28731753 DOI: 10.1103/physrevlett.119.012501] [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: 12/14/2016] [Indexed: 06/07/2023]
Abstract
New measurements of the beam normal single spin asymmetry in the electron elastic and quasielastic scattering on the proton and deuteron, respectively, at large backward angles and at ⟨Q^{2}⟩=0.22 (GeV/c)^{2} and ⟨Q^{2}⟩=0.35 ( GeV/c)^{2} are reported. The experimentally observed asymmetries are compared with the theoretical calculation of Pasquini and Vanderhaeghen [Phys. Rev. C 70, 045206 (2004).PRVCAN0556-281310.1103/PhysRevC.70.045206]. The agreement of the measurements with the theoretical calculations shows a dominance of the inelastic intermediate excited states of the nucleon, πN and the Δ resonance. The measurements explore a new, important parameter region of the exchanged virtual photon virtualities.
Collapse
Affiliation(s)
- D Balaguer Ríos
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - K Aulenbacher
- 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
| | - J Diefenbach
- 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
| | - J H Lee
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, 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
| | - U Müller
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - 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
| | - L Capozza
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 36, D-55099 Mainz, Germany
| | - 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, J.J. Becherweg 36, D-55099 Mainz, Germany
| | - J Arvieux
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - M A El-Yakoubi
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - R Frascaria
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - R Kunne
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - M Morlet
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - S Ong
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - J van de Wiele
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - S Kowalski
- Laboratory for Nuclear Science and Department of Physics, MIT, Cambridge, Massachusetts 02139, USA
| | - Y Prok
- Laboratory for Nuclear Science and Department of Physics, MIT, Cambridge, Massachusetts 02139, USA
| |
Collapse
|
3
|
Balaguer Ríos D, Aulenbacher K, Baunack S, Diefenbach J, Gläser B, von Harrach D, Imai Y, Kabuß EM, Kothe R, Lee J, Merkel H, Mora Espí M, Müller U, Schilling E, Weinrich C, Capozza L, Maas F, Arvieux J, El-Yakoubi M, Frascaria R, Kunne R, Ong S, van de Wiele J, Kowalski S, Prok Y. Measurement of the parity violating asymmetry in the quasielastic electron-deuteron scattering and improved determination of the magnetic strange form factor and the isovector anapole radiative correction. Int J Clin Exp Med 2016. [DOI: 10.1103/physrevd.94.051101] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
4
|
Baunack S, Aulenbacher K, Balaguer Ríos D, Capozza L, Diefenbach J, Gläser B, von Harrach D, Imai Y, Kabuss EM, Kothe R, Lee JH, Merkel H, Mora Espí MC, Müller U, Schilling E, Stephan G, Weinrich C, Arvieux J, El-Yakoubi MA, Frascaria R, Kunne R, Maas FE, Morlet M, Ong S, van de Wiele J, Kowalski S, Prok Y, Taylor S. Measurement of strange quark contributions to the vector form factors of the proton at Q2 = 0.22 (GeV / c)2. Phys Rev Lett 2009; 102:151803. [PMID: 19518619 DOI: 10.1103/physrevlett.102.151803] [Citation(s) in RCA: 7] [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: 11/17/2008] [Indexed: 05/27/2023]
Abstract
A new measurement of the parity violating asymmetry in elastic electron scattering on hydrogen at backward angles and at a four momentum transfer of Q;{2} = 0.22 (Ge V / c);{2} is reported here. The measured asymmetry is A_{LR} = (-17.23 +/- 0.82_{stat} +/- 0.89_{syst}) x 10;{-6}. The standard model prediction assuming no strangeness is A_{0} = (-15.87 +/- 1.22) x 10;{-6}. In combination with previous results from measurements at forward angles, it is possible to disentangle for the first time the strange form factors at this momentum transfer, G_{E};{s} = 0.050 +/- 0.038 +/- 0.019 and G_{M};{s} = -0.14 +/- 0.11 +/- 0.11.
Collapse
Affiliation(s)
- S Baunack
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Armstrong DS, Arvieux J, Asaturyan R, Averett T, Bailey SL, Batigne G, Beck DH, Beise EJ, Benesch J, Bimbot L, Birchall J, Biselli A, Bosted P, Boukobza E, Breuer H, Carlini R, Carr R, Chant N, Chao YC, Chattopadhyay S, Clark R, Covrig S, Cowley A, Dale D, Davis C, Falk W, Finn JM, Forest T, Franklin G, Furget C, Gaskell D, Grames J, Griffioen KA, Grimm K, Guillon B, Guler H, Hannelius L, Hasty R, Hawthorne Allen A, Horn T, Johnston K, Jones M, Kammel P, Kazimi R, King PM, Kolarkar A, Korkmaz E, Korsch W, Kox S, Kuhn J, Lachniet J, Lee L, Lenoble J, Liatard E, Liu J, Loupias B, Lung A, MacLachlan GA, Marchand D, Martin JW, McFarlane KW, McKee DW, McKeown RD, Merchez F, Mkrtchyan H, Moffit B, Morlet M, Nakagawa I, Nakahara K, Nakos M, Neveling R, Niccolai S, Ong S, Page S, Papavassiliou V, Pate SF, Phillips SK, Pitt ML, Poelker M, Porcelli TA, Quéméner G, Quinn B, Ramsay WD, Rauf AW, Real JS, Roche J, Roos P, Rutledge GA, Secrest J, Simicevic N, Smith GR, Spayde DT, Stepanyan S, Stutzman M, Sulkosky V, Tadevosyan V, Tieulent R, van de Wiele J, van Oers W, Voutier E, Vulcan W, Warren G, Wells SP, Williamson SE, Wood SA, Yan C, Yun J, Zeps V. Strange-quark contributions to parity-violating asymmetries in the forward g0 electron-proton scattering experiment. Phys Rev Lett 2005; 95:092001. [PMID: 16197209 DOI: 10.1103/physrevlett.95.092001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Indexed: 05/04/2023]
Abstract
We have measured parity-violating asymmetries in elastic electron-proton scattering over the range of momentum transfers 0.12 < or =Q2 < or =1.0 GeV2. These asymmetries, arising from interference of the electromagnetic and neutral weak interactions, are sensitive to strange-quark contributions to the currents of the proton. The measurements were made at Jefferson Laboratory using a toroidal spectrometer to detect the recoiling protons from a liquid hydrogen target. The results indicate nonzero, Q2 dependent, strange-quark contributions and provide new information beyond that obtained in previous experiments.
Collapse
Affiliation(s)
- D S Armstrong
- Department of Physics, College of William and Mary, Williamsburg, VA 23187, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Maas FE, Aulenbacher K, Baunack S, Capozza L, Diefenbach J, Gläser B, Hammel T, von Harrach D, Imai Y, Kabuss EM, Kothe R, Lee JH, Lorente A, Schilling E, Schwaab D, Sikora M, Stephan G, Weber G, Weinrich C, Altarev I, Arvieux J, El-Yakoubi M, Frascaria R, Kunne R, Morlet M, Ong S, van de Wiele J, Kowalski S, Plaster B, Suleiman R, Taylor S. Evidence for strange-quark contributions to the nucleon's form factors at Q2=0.108 (GeV/c)2. Phys Rev Lett 2005; 94:152001. [PMID: 15904134 DOI: 10.1103/physrevlett.94.152001] [Citation(s) in RCA: 10] [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: 12/14/2004] [Indexed: 05/02/2023]
Abstract
We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of Q(2)=0.108 (GeV/c)(2) and at a forward electron scattering angle of 30 degrees <theta(e)<40 degrees . The measured asymmetry is A(LR)(e-->p)=[-1.36+/-0.29(stat)+/-0.13(syst)]x10(-6). The expectation from the standard model assuming no strangeness contribution to the vector current is A(0)=(-2.06+/-0.14)x10(-6). We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher Q2. We have extracted the strangeness contribution to the electromagnetic form factors from our data to be G(s)(E)+0.106G(s)(M)=0.071+/-0.036 at Q(2)=0.108 (GeV/c)(2). We again find the value for G(s)(E)+0.106G(s)(M) to be positive, this time at an improved significance level of two sigma.
Collapse
Affiliation(s)
- F E Maas
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, JJ Becherweg 45, D-55099 Mainz, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Maas FE, Achenbach P, Aulenbacher K, Baunack S, Capozza L, Diefenbach J, Grimm K, Imai Y, Hammel T, von Harrach D, Kabuss EM, Kothe R, Lee JH, Lorente A, Lopes Ginja A, Nungesser L, Schilling E, Stephan G, Weinrich C, Altarev I, Arvieux J, Collin B, Frascaria R, Guidal M, Kunne R, Marchand D, Morlet M, Ong S, van de Wiele J, Kowalski S, Plaster B, Suleiman R, Taylor S. Measurement of strange-quark contributions to the nucleon's form factors at Q(2) = 0.230 (GeV/c)(2). Phys Rev Lett 2004; 93:022002. [PMID: 15323904 DOI: 10.1103/physrevlett.93.022002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Indexed: 05/24/2023]
Abstract
We report on a measurement of the parity-violating asymmetry in the scattering of longitudinally polarized electrons on unpolarized protons at a Q2 of 0.230 (GeV/c)(2) and a scattering angle of theta (e) = 30 degrees - 40 degrees. Using a large acceptance fast PbF2 calorimeter with a solid angle of delta omega = 0.62 sr, the A4 experiment is the first parity violation experiment to count individual scattering events. The measured asymmetry is A(phys)=(-5.44+/-0.54(stat)+/-0.26(sys))x10(-6). The standard model expectation assuming no strangeness contributions to the vector form factors is A(0) = (-6.30+/-0.43) x 10(-6). The difference is a direct measurement of the strangeness contribution to the vector form factors of the proton. The extracted value is G(s)(E) + 0.225G(s)(M) = 0.039+/-0.034 or F(s)(1) + 0.130F(s)(2) = 0.032+/-0.028.
Collapse
Affiliation(s)
- F E Maas
- Institut für Kernphysik, Johannes Gutenberg Universität Mainz, J. J. Becherweg 45, D-55099 Mainz, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|