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Androić D, Armstrong DS, Arvieux J, Bailey SL, Beck DH, Beise EJ, Benesch J, Benmokhtar F, Bimbot L, Birchall J, Bosted P, Breuer H, Capuano CL, Chao YC, Coppens A, Davis CA, Ellis C, Flores G, Franklin G, Furget C, Gaskell D, Gericke MTW, Grames J, Guillard G, Hansknecht J, Horn T, Jones MK, King PM, Korsch W, Kox S, Lee L, Liu J, Lung A, Mammei J, Martin JW, McKeown RD, Micherdzinska A, Mihovilovic M, Mkrtchyan H, Muether M, Page SA, Papavassiliou V, Pate SF, Phillips SK, Pillot P, Pitt ML, Poelker M, Quinn B, Ramsay WD, Real JS, Roche J, Roos P, Schaub J, Seva T, Simicevic N, Smith GR, Spayde DT, Stutzman M, Suleiman R, Tadevosyan V, van Oers WTH, Versteegen M, Voutier E, Vulcan W, Wells SP, Williamson SE, Wood SA, Pasquini B, Vanderhaeghen M. Transverse beam spin asymmetries at backward angles in elastic electron-proton and quasielastic electron-deuteron scattering. Phys Rev Lett 2011; 107:022501. [PMID: 21797598 DOI: 10.1103/physrevlett.107.022501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Indexed: 05/31/2023]
Abstract
We have measured the beam-normal single-spin asymmetries in elastic scattering of transversely polarized electrons from the proton, and performed the first measurement in quasielastic scattering on the deuteron, at backward angles (lab scattering angle of 108°) for Q² = 0.22 GeV²/c² and 0.63 GeV²/c² at beam energies of 362 and 687 MeV, respectively. The asymmetry arises due to the imaginary part of the interference of the two-photon exchange amplitude with that of single-photon exchange. Results for the proton are consistent with a model calculation which includes inelastic intermediate hadronic (πN) states. An estimate of the beam-normal single-spin asymmetry for the scattering from the neutron is made using a quasistatic deuterium approximation, and is also in agreement with theory.
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Affiliation(s)
- D Androić
- Department of Physics, University of Zagreb, Zagreb HR-41001, Croatia
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Meziane M, Brash EJ, Gilman R, Jones MK, Luo W, Pentchev L, Perdrisat CF, Puckett AJR, Punjabi V, Wesselmann FR, Ahmidouch A, Albayrak I, Aniol KA, Arrington J, Asaturyan A, Ates O, Baghdasaryan H, Benmokhtar F, Bertozzi W, Bimbot L, Bosted P, Boeglin W, Butuceanu C, Carter P, Chernenko S, Christy E, Commisso M, Cornejo JC, Covrig S, Danagoulian S, Daniel A, Davidenko A, Day D, Dhamija S, Dutta D, Ent R, Frullani S, Fenker H, Frlez E, Garibaldi F, Gaskell D, Gilad S, Goncharenko Y, Hafidi K, Hamilton D, Higinbotham DW, Hinton W, Horn T, Hu B, Huang J, Huber GM, Jensen E, Kang H, Keppel C, Khandaker M, King P, Kirillov D, Kohl M, Kravtsov V, Kumbartzki G, Li Y, Mamyan V, Margaziotis DJ, Markowitz P, Marsh A, Matulenko Y, Maxwell J, Mbianda G, Meekins D, Melnik Y, Miller J, Mkrtchyan A, Mkrtchyan H, Moffit B, Moreno O, Mulholland J, Narayan A, Nedev S, Piasetzky E, Pierce W, Piskunov NM, Prok Y, Ransome RD, Razin DS, Reimer PE, Reinhold J, Rondon O, Shabestari M, Shahinyan A, Shestermanov K, Širca S, Sitnik I, Smykov L, Smith G, Solovyev L, Solvignon P, Subedi R, Suleiman R, Tomasi-Gustafsson E, Vasiliev A, Vanderhaeghen M, Veilleux M, Wojtsekhowski BB, Wood S, Ye Z, Zanevsky Y, Zhang X, Zhang Y, Zheng X, Zhu L. Search for effects beyond the born approximation in polarization transfer observables in e(over→)p elastic scattering. Phys Rev Lett 2011; 106:132501. [PMID: 21520982 DOI: 10.1103/physrevlett.106.132501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Indexed: 05/30/2023]
Abstract
Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, G(E)/G(M), obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic H(e[over →],e(')p[over →]) reaction for three different beam energies at a Q(2)=2.5 GeV(2), spanning a wide range of the kinematic parameter ε. The ratio R, which equals μ(p)G(E)/G(M) in the Born approximation, is found to be independent of ε at the 1.5% level. The ε dependence of the longitudinal polarization transfer component P(ℓ) shows an enhancement of (2.3±0.6)% relative to the Born approximation at large ε.
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Affiliation(s)
- M Meziane
- The College of William and Mary, Williamsburg, Virginia 23187, USA.
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Gorchtein M, Lorcé C, Pasquini B, Vanderhaeghen M. Light-front interpretation of proton generalized polarizabilities. Phys Rev Lett 2010; 104:112001. [PMID: 20366465 DOI: 10.1103/physrevlett.104.112001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2009] [Indexed: 05/29/2023]
Abstract
We extend the recently developed formalism to extract light-front quark charge densities from nucleon form factor data to the deformations of these quark charge densities when applying an external electric field. We show that the resulting induced polarizations can be extracted from proton generalized polarizabilities. The available data for the generalized electric polarizability of the proton yield a pronounced structure in its induced polarization at large transverse distances, which will be pinned down by forthcoming high precision virtual Compton scattering experiments.
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Affiliation(s)
- M Gorchtein
- Indiana University, Bloomington, Indiana 47408, USA
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4
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Chen S, Avakian H, Burkert VD, Eugenio P, Adams G, Amarian M, Ambrozewicz P, Anghinolfi M, Asryan G, Bagdasaryan H, Baillie N, Ball JP, Baltzell NA, Barrow S, Batourine V, Battaglieri M, Beard K, Bedlinskiy I, Bektasoglu M, Bellis M, Benmouna N, Berman BL, Biselli AS, Bonner BE, Bouchigny S, Boiarinov S, Bosted P, Bradford R, Branford D, Briscoe WJ, Brooks WK, Bültmann S, Butuceanu C, Calarco JR, Careccia SL, Carman DS, Carnahan B, Cazes A, Cole PL, Collins P, Coltharp P, Cords D, Corvisiero P, Crabb D, Crannell H, Crede V, Cummings JP, DeMasi R, DeVita R, De Sanctis E, Degtyarenko PV, Denizli H, Dennis L, Deur A, Dharmawardane KV, Dhuga KS, Djalali C, Dodge GE, Donnelly J, Doughty D, Dugger M, Dytman S, Dzyubak OP, Egiyan H, Egiyan KS, El Fassi L, Elouadrhiri L, Fatemi R, Fedotov G, Feldman G, Feuerbach RJ, Forest TA, Funsten H, Garçon M, Gavalian G, Gilfoyle GP, Giovanetti KL, Girod FX, Goetz JT, Golovatch E, Gonenc A, Gothe RW, Griffioen KA, Guidal M, Guillo M, Guler N, Guo L, Gyurjyan V, Hadjidakis C, Hafidi K, Hakobyan H, Hakobyan RS, Hardie J, Heddle D, Hersman FW, Hicks K, Hleiqawi I, Holtrop M, Huertas M, Hyde-Wright CE, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Ito MM, Jenkins D, Jo HS, Joo K, Juengst HG, Keith C, Kellie JD, Khandaker M, Kim KY, Kim K, Kim W, Klein A, Klein FJ, Klusman M, Kossov M, Kramer LH, Kubarovsky V, Kuhn J, Kuhn SE, Kuleshov SV, Lachniet J, Laget JM, Langheinrich J, Lawrence D, Li J, Lima ACS, Livingston K, Lu H, Lukashin K, MacCormick M, Markov N, McAleer S, McKinnon B, McNabb JWC, Mecking BA, Mestayer MD, Meyer CA, Mibe T, Mikhailov K, Minehart R, Mirazita M, Miskimen R, Mokeev V, Morand L, Morrow SA, Moteabbed M, Mueller J, Mutchler GS, Nadel-Turonski P, Napolitano J, Nasseripour R, Natasha N, Niccolai S, Niculescu G, Niculescu I, Niczyporuk BB, Niroula MR, Niyazov RA, Nozar M, O'Rielly GV, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Paterson C, Philips SA, Pierce J, Pivnyuk N, Pocanic D, Pogorelko O, Polli E, Popa I, Pozdniakov S, Preedom BM, Price JW, Prok Y, Protopopescu D, Qin LM, Raue BA, Riccardi G, Ricco G, Ripani M, Ritchie BG, Ronchetti F, Rosner G, Rossi P, Rowntree D, Rubin PD, Sabatié F, Salgado C, Santoro JP, Sapunenko V, Schumacher RA, Serov VS, Sharabian YG, Shaw J, Shvedunov NV, Skabelin AV, Smith ES, Smith LC, Sober DI, Stavinsky A, Stepanyan SS, Stepanyan S, Stokes BE, Stoler P, Strakovsky II, Strauch S, Suleiman R, Taiuti M, Tedeschi DJ, Thoma U, Tkabladze A, Tkachenko S, Todor L, Tur C, Ungaro M, Vanderhaeghen M, Vineyard MF, Vlassov AV, Watts DP, Weinstein LB, Weygand DP, Williams M, Wolin E, Wood MH, Yegneswaran A, Yun J, Zana L, Zhang J, Zhao B, Zhao Z. Measurement of deeply virtual compton scattering with a polarized-proton target. Phys Rev Lett 2006; 97:072002. [PMID: 17026221 DOI: 10.1103/physrevlett.97.072002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Indexed: 05/12/2023]
Abstract
The longitudinal target-spin asymmetry AUL for the exclusive electroproduction of high-energy photons was measured for the first time in ep-->e;'pgamma. The data have been accumulated at JLab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH3 target. A significant azimuthal angular dependence was observed, resulting from the interference of the deeply virtual Compton scattering and Bethe-Heitler processes. The amplitude of the sinvarphi moment is 0.252+/-0.042stat+/-0.020sys. Theoretical calculations are in good agreement with the magnitude and the kinematic dependence of the target-spin asymmetry, which is sensitive to the generalized parton distributions H and H.
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Affiliation(s)
- S Chen
- Florida State University, Tallahassee, Florida 32306, USA
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Laveissière G, Todor L, Degrande N, Jaminion S, Jutier C, Di Salvo R, Van Hoorebeke L, Alexa LC, Anderson BD, Aniol KA, Arundell K, Audit G, Auerbach L, Baker FT, Baylac M, Berthot J, Bertin PY, Bertozzi W, Bimbot L, Boeglin WU, Brash EJ, Breton V, Breuer H, Burtin E, Calarco JR, Cardman LS, Cavata C, Chang CC, Chen JP, Chudakov E, Cisbani E, Dale DS, de Jager CW, De Leo R, Deur A, d'Hose N, Dodge GE, Domingo JJ, Elouadrhiri L, Epstein MB, Ewell LA, Finn JM, Fissum KG, Fonvieille H, Fournier G, Frois B, Frullani S, Furget C, Gao H, Gao J, Garibaldi F, Gasparian A, Gilad S, Gilman R, Glamazdin A, Glashausser C, Gomez J, Gorbenko V, Grenier P, Guichon PAM, Hansen JO, Holmes R, Holtrop M, Howell C, Huber GM, Hyde-Wright CE, Incerti S, Iodice M, Jardillier J, Jones MK, Kahl W, Kato S, Katramatou AT, Kelly JJ, Kerhoas S, Ketikyan A, Khayat M, Kino K, Kox S, Kramer LH, Kumar KS, Kumbartzki G, Kuss M, Leone A, LeRose JJ, Liang M, Lindgren RA, Liyanage N, Lolos GJ, Lourie RW, Madey R, Maeda K, Malov S, Manley DM, Marchand C, Marchand D, Margaziotis DJ, Markowitz P, Marroncle J, Martino J, McCormick K, McIntyre J, Mehrabyan S, Merchez F, Meziani ZE, Michaels R, Miller GW, Mougey JY, Nanda SK, Neyret D, Offermann EAJM, Papandreou Z, Pasquini B, Perdrisat CF, Perrino R, Petratos GG, Platchkov S, Pomatsalyuk R, Prout DL, Punjabi VA, Pussieux T, Quémenér G, Ransome RD, Ravel O, Real JS, Renard F, Roblin Y, Rowntree D, Rutledge G, Rutt PM, Saha A, Saito T, Sarty AJ, Serdarevic A, Smith T, Smirnov G, Soldi K, Sorokin P, Souder PA, Suleiman R, Templon JA, Terasawa T, Tieulent R, Tomasi-Gustaffson E, Tsubota H, Ueno H, Ulmer PE, Urciuoli GM, Vanderhaeghen M, Van De Vyver R, Van der Meer RLJ, Vernin P, Vlahovic B, Voskanyan H, Voutier E, Watson JW, Weinstein LB, Wijesooriya K, Wilson R, Wojtsekhowski BB, Zainea DG, Zhang WM, Zhao J, Zhou ZL. Measurement of the generalized polarizabilities of the proton in virtual Compton scattering at Q2=0.92 and 1.76 GeV2. Phys Rev Lett 2004; 93:122001. [PMID: 15447252 DOI: 10.1103/physrevlett.93.122001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2003] [Indexed: 05/24/2023]
Abstract
We report a virtual Compton scattering study of the proton at low c.m. energies. We have determined the structure functions P(LL)-P(TT)/epsilon and P(LT), and the electric and magnetic generalized polarizabilities (GPs) alpha(E)(Q2) and beta(M)(Q2) at momentum transfer Q(2)=0.92 and 1.76 GeV2. The electric GP shows a strong falloff with Q2, and its global behavior does not follow a simple dipole form. The magnetic GP shows a rise and then a falloff; this can be interpreted as the dominance of a long-distance diamagnetic pion cloud at low Q2, compensated at higher Q2 by a paramagnetic contribution from piN intermediate states.
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Affiliation(s)
- G Laveissière
- Université Blaise Pascal/IN2P3, F-63177 Aubière, France
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Chen YC, Afanasev A, Brodsky SJ, Carlson CE, Vanderhaeghen M. Partonic calculation of the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer. Phys Rev Lett 2004; 93:122301. [PMID: 15447254 DOI: 10.1103/physrevlett.93.122301] [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: 03/04/2004] [Indexed: 05/24/2023]
Abstract
We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer through the scattering off a parton in the proton. We relate the two-photon exchange amplitude to the generalized parton distributions which appear in hard exclusive processes. We find that when taking the polarization transfer determinations of the form factors as input, adding in the 2-photon correction does reproduce the Rosenbluth cross sections.
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Affiliation(s)
- Y-C Chen
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
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Guichon PAM, Vanderhaeghen M. How to reconcile the Rosenbluth and the polarization transfer methods in the measurement of the proton form factors. Phys Rev Lett 2003; 91:142303. [PMID: 14611519 DOI: 10.1103/physrevlett.91.142303] [Citation(s) in RCA: 13] [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: 06/01/2003] [Indexed: 05/24/2023]
Abstract
The apparent discrepancy between the Rosenbluth and the polarization transfer methods for the ratio of the electric to magnetic proton form factors can be explained by a two-photon exchange correction which does not destroy the linearity of the Rosenbluth plot. Though intrinsically small, of the order of a few percent of the cross section, this correction is accidentally amplified in the case of the Rosenbluth method.
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Affiliation(s)
- P A M Guichon
- SPhN/DAPNIA, CEA Saclay, F91191 Gif sur Yvette, France
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Abstract
We study the double deeply virtual Compton scattering (DDVCS) process off the nucleon, through the scattering of a space-like virtual photon with large virtuality resulting in the production of a time-like virtual photon, decaying into an e(+)e(-) pair. This process is expressed in the Bjorken regime in terms of generalized parton distributions (GPDs), and it is shown that by varying the invariant mass of the lepton pair, one can directly extract the GPDs from the observables. We give predictions for the DDVCS cross section and beam helicity asymmetry and discuss its experimental feasibility.
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Affiliation(s)
- M Guidal
- Institut de Physique Nucléaire, F-91406 Orsay, France
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Frankfurt LL, Polyakov MV, Strikman M, Vanderhaeghen M. Hard exclusive electroproduction of decuplet baryons in the large N(c) limit. Phys Rev Lett 2000; 84:2589-2592. [PMID: 11017276 DOI: 10.1103/physrevlett.84.2589] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/1999] [Indexed: 05/23/2023]
Abstract
The cross sections and transverse spin asymmetries in the hard exclusive electroproduction of decuplet baryons are calculated in the large N(c) limit and found to be comparable to that of octet baryons. Large N(c) selection rules for the production amplitudes are derived, leading to new sensitive tests of the spin aspects of the QCD chiral dynamics both in the nonstrange and strange sectors. Importance of such studies for the reliable extraction of the pion form factor from pion electroproduction is explained.
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Affiliation(s)
- LL Frankfurt
- School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv, Israel
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Ryckebusch J, Machenil L, Vanderhaeghen M, Waroquier M. Reply to "Comment on 'Multinucleon mechanisms in ( gamma,N) and ( gamma,NN) reactions' ". Phys Rev C Nucl Phys 1996; 54:3313-3314. [PMID: 9971715 DOI: 10.1103/physrevc.54.3313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Ryckebusch J, Machenil L, Vanderhaeghen M, Waroquier M. Multinucleon mechanisms in ( gamma,N) and ( gamma,NN) reactions. Phys Rev C Nucl Phys 1994; 49:2704-2715. [PMID: 9969519 DOI: 10.1103/physrevc.49.2704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Ryckebusch J, Heyde K, Machenil L, Ryckbosch D, Vanderhaeghen M, Waroquier M. Meson exchange currents and high-resolution ( gamma,p) reactions. Phys Rev C Nucl Phys 1992; 46:R829-R832. [PMID: 9968223 DOI: 10.1103/physrevc.46.r829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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