Towards a resolution of the proton form factor problem: New electron and positron scattering data

D. Adikaram; D. Rimal; L. B. Weinstein; B. Raue; P. Khetarpal; R. P. Bennett; J. Arrington; W. K. Brooks; K. P. Adhikari; A. V. Afanasev; M. J. Amaryan; M. D. Anderson; S. Anefalos Pereira; H. Avakian; J. Ball; M. Battaglieri; I. Bedlinskiy; A. S. Biselli; J. Bono; S. Boiarinov; W. J. Briscoe; V. D. Burkert; D. S. Carman; S. Careccia; A. Celentano; S. Chandavar; G. Charles; L. Colaneri; P. L. Cole; M. Contalbrigo; V. Crede; A. D'Angelo; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; G. E. Dodge; R. Dupre; H. Egiyan; A. El Alaoui; L. El Fassi; L. Elouadrhiri; P. Eugenio; G. Fedotov; S. Fegan; A. Filippi; J. A. Fleming; A. Fradi; B. Garillon; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; J. T. Goetz; W. Gohn; E. Golovatch; R. W. Gothe; K. A. Griffioen; B. Guegan; M. Guidal; L. Guo; K. Hafidi; H. Hakobyan; C. Hanretty; N. Harrison; M. Hattawy; K. Hicks; M. Holtrop; S. M. Hughes; C. E. Hyde; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; D. Jenkins; H. Jiang; H. S. Jo; K. Joo; S. Joosten; N. Kalantarians; D. Keller; M. Khandaker; A. Kim; W. Kim; A. Klein; F. J. Klein; S. Koirala; V. Kubarovsky; S. E. Kuhn; K. Livingston; H. Y. Lu; I. J.D. Macgregor; N. Markov; P. Mattione; M. Mayer; B. McKinnon; M. D. Mestayer; C. A. Meyer; M. Mirazita; V. Mokeev; R. A. Montgomery; C. I. Moody; H. Moutarde; A. Movsisyan; C. Munoz Camacho; P. Nadel-Turonski; S. Niccolai; G. Niculescu; M. Osipenko; A. I. Ostrovidov; K. Park; E. Pasyuk; C. Peña; S. Pisano; O. Pogorelko; J. W. Price; S. Procureur; Y. Prok; D. Protopopescu; A. J.R. Puckett; M. Ripani; A. Rizzo; G. Rosner; P. Rossi; P. Roy; F. Sabatié; C. Salgado; D. Schott; R. A. Schumacher; E. Seder; Y. G. Sharabian; A. Simonyan; I. Skorodumina; E. S. Smith; G. D. Smith; D. I. Sober; D. Sokhan; N. Sparveris; S. Stepanyan; P. Stoler; S. Strauch; V. Sytnik; M. Taiuti; Ye Tian; A. Trivedi; M. Ungaro; H. Voskanyan; E. Voutier; N. K. Walford; D. P. Watts; X. Wei; M. H. Wood; N. Zachariou; L. Zana; J. Zhang; Z. W. Zhao; I. Zonta

doi:10.1103/PhysRevLett.114.062003

Towards a resolution of the proton form factor problem: New electron and positron scattering data

D. Adikaram, D. Rimal, L. B. Weinstein, B. Raue, P. Khetarpal, R. P. Bennett, J. Arrington, W. K. Brooks, K. P. Adhikari, A. V. Afanasev, M. J. Amaryan, M. D. Anderson, S. Anefalos Pereira, H. Avakian, J. Ball, M. Battaglieri, I. Bedlinskiy, A. S. Biselli, J. Bono, S. BoiarinovW. J. Briscoe, V. D. Burkert, D. S. Carman, S. Careccia, A. Celentano, S. Chandavar, G. Charles, L. Colaneri, P. L. Cole, M. Contalbrigo, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, G. E. Dodge, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, A. Filippi, J. A. Fleming, A. Fradi, B. Garillon, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, J. T. Goetz, W. Gohn, E. Golovatch, R. W. Gothe, K. A. Griffioen, B. Guegan, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, C. Hanretty, N. Harrison, M. Hattawy, K. Hicks, M. Holtrop, S. M. Hughes, C. E. Hyde, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, D. Jenkins, H. Jiang, H. S. Jo, K. Joo, S. Joosten, N. Kalantarians, D. Keller, M. Khandaker, A. Kim, W. Kim, A. Klein, F. J. Klein, S. Koirala, V. Kubarovsky, S. E. Kuhn, K. Livingston, H. Y. Lu, I. J.D. Macgregor, N. Markov, P. Mattione, M. Mayer, B. McKinnon, M. D. Mestayer, C. A. Meyer, M. Mirazita, V. Mokeev, R. A. Montgomery, C. I. Moody, H. Moutarde, A. Movsisyan, C. Munoz Camacho, P. Nadel-Turonski, S. Niccolai, G. Niculescu, M. Osipenko, A. I. Ostrovidov, K. Park, E. Pasyuk, C. Peña, S. Pisano, O. Pogorelko, J. W. Price, S. Procureur, Y. Prok, D. Protopopescu, A. J.R. Puckett, M. Ripani, A. Rizzo, G. Rosner, P. Rossi, P. Roy, F. Sabatié, C. Salgado, D. Schott, R. A. Schumacher, E. Seder, Y. G. Sharabian, A. Simonyan, I. Skorodumina, E. S. Smith, G. D. Smith, D. I. Sober, D. Sokhan, N. Sparveris, S. Stepanyan, P. Stoler, S. Strauch, V. Sytnik, M. Taiuti, Ye Tian, A. Trivedi, M. Ungaro, H. Voskanyan, E. Voutier, N. K. Walford, D. P. Watts, X. Wei, M. H. Wood, N. Zachariou, L. Zana, J. Zhang, Z. W. Zhao, I. Zonta

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Abstract

There is a significant discrepancy between the values of the proton electric form factor, GEp, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GEp from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization and momentum transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing at Q2=1.45GeV2. This measurement is consistent with the size of the form factor discrepancy at Q2≈1.75GeV2 and with hadronic calculations including nucleon and Δ intermediate states, which have been shown to resolve the discrepancy up to 2-3GeV2.

Original language	English
Article number	062003
Journal	Physical Review Letters
Volume	114
Issue number	6
DOIs	https://doi.org/10.1103/PhysRevLett.114.062003
State	Published - 10 Feb 2015

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10.1103/PhysRevLett.114.062003

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Adikaram, D., Rimal, D., Weinstein, L. B., Raue, B., Khetarpal, P., Bennett, R. P., Arrington, J., Brooks, W. K., Adhikari, K. P., Afanasev, A. V., Amaryan, M. J., Anderson, M. D., Anefalos Pereira, S., Avakian, H., Ball, J., Battaglieri, M., Bedlinskiy, I., Biselli, A. S., Bono, J., ... Zonta, I. (2015). Towards a resolution of the proton form factor problem: New electron and positron scattering data. Physical Review Letters, 114(6), Article 062003. https://doi.org/10.1103/PhysRevLett.114.062003

@article{17cf62bb506849bd98095c371d4750b9,

title = "Towards a resolution of the proton form factor problem: New electron and positron scattering data",

abstract = "There is a significant discrepancy between the values of the proton electric form factor, GEp, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GEp from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization and momentum transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing at Q2=1.45GeV2. This measurement is consistent with the size of the form factor discrepancy at Q2≈1.75GeV2 and with hadronic calculations including nucleon and Δ intermediate states, which have been shown to resolve the discrepancy up to 2-3GeV2.",

author = "D. Adikaram and D. Rimal and Weinstein, {L. B.} and B. Raue and P. Khetarpal and Bennett, {R. P.} and J. Arrington and Brooks, {W. K.} and Adhikari, {K. P.} and Afanasev, {A. V.} and Amaryan, {M. J.} and Anderson, {M. D.} and {Anefalos Pereira}, S. and H. Avakian and J. Ball and M. Battaglieri and I. Bedlinskiy and Biselli, {A. S.} and J. Bono and S. Boiarinov and Briscoe, {W. J.} and Burkert, {V. D.} and Carman, {D. S.} and S. Careccia and A. Celentano and S. Chandavar and G. Charles and L. Colaneri and Cole, {P. L.} and M. Contalbrigo and V. Crede and A. D'Angelo and N. Dashyan and {De Vita}, R. and {De Sanctis}, E. and A. Deur and C. Djalali and Dodge, {G. E.} and R. Dupre and H. Egiyan and {El Alaoui}, A. and {El Fassi}, L. and L. Elouadrhiri and P. Eugenio and G. Fedotov and S. Fegan and A. Filippi and Fleming, {J. A.} and A. Fradi and B. Garillon and Gilfoyle, {G. P.} and Giovanetti, {K. L.} and Girod, {F. X.} and Goetz, {J. T.} and W. Gohn and E. Golovatch and Gothe, {R. W.} and Griffioen, {K. A.} and B. Guegan and M. Guidal and L. Guo and K. Hafidi and H. Hakobyan and C. Hanretty and N. Harrison and M. Hattawy and K. Hicks and M. Holtrop and Hughes, {S. M.} and Hyde, {C. E.} and Y. Ilieva and Ireland, {D. G.} and Ishkhanov, {B. S.} and D. Jenkins and H. Jiang and Jo, {H. S.} and K. Joo and S. Joosten and N. Kalantarians and D. Keller and M. Khandaker and A. Kim and W. Kim and A. Klein and Klein, {F. J.} and S. Koirala and V. Kubarovsky and Kuhn, {S. E.} and K. Livingston and Lu, {H. Y.} and Macgregor, {I. J.D.} and N. Markov and P. Mattione and M. Mayer and B. McKinnon and Mestayer, {M. D.} and Meyer, {C. A.} and M. Mirazita and V. Mokeev and Montgomery, {R. A.} and Moody, {C. I.} and H. Moutarde and A. Movsisyan and Camacho, {C. Munoz} and P. Nadel-Turonski and S. Niccolai and G. Niculescu and M. Osipenko and Ostrovidov, {A. I.} and K. Park and E. Pasyuk and C. Pe{\~n}a and S. Pisano and O. Pogorelko and Price, {J. W.} and S. Procureur and Y. Prok and D. Protopopescu and Puckett, {A. J.R.} and M. Ripani and A. Rizzo and G. Rosner and P. Rossi and P. Roy and F. Sabati{\'e} and C. Salgado and D. Schott and Schumacher, {R. A.} and E. Seder and Sharabian, {Y. G.} and A. Simonyan and I. Skorodumina and Smith, {E. S.} and Smith, {G. D.} and Sober, {D. I.} and D. Sokhan and N. Sparveris and S. Stepanyan and P. Stoler and S. Strauch and V. Sytnik and M. Taiuti and Ye Tian and A. Trivedi and M. Ungaro and H. Voskanyan and E. Voutier and Walford, {N. K.} and Watts, {D. P.} and X. Wei and Wood, {M. H.} and N. Zachariou and L. Zana and J. Zhang and Zhao, {Z. W.} and I. Zonta",

note = "Publisher Copyright: {\textcopyright} 2015 American Physical Society.",

year = "2015",

month = feb,

day = "10",

doi = "10.1103/PhysRevLett.114.062003",

language = "English",

volume = "114",

journal = "Physical Review Letters",

issn = "0031-9007",

publisher = "American Physical Society",

number = "6",

}

Adikaram, D, Rimal, D, Weinstein, LB, Raue, B, Khetarpal, P, Bennett, RP, Arrington, J, Brooks, WK, Adhikari, KP, Afanasev, AV, Amaryan, MJ, Anderson, MD, Anefalos Pereira, S, Avakian, H, Ball, J, Battaglieri, M, Bedlinskiy, I, Biselli, AS, Bono, J, Boiarinov, S, Briscoe, WJ, Burkert, VD, Carman, DS, Careccia, S, Celentano, A, Chandavar, S, Charles, G, Colaneri, L, Cole, PL, Contalbrigo, M, Crede, V, D'Angelo, A, Dashyan, N, De Vita, R, De Sanctis, E, Deur, A, Djalali, C, Dodge, GE, Dupre, R, Egiyan, H, El Alaoui, A, El Fassi, L, Elouadrhiri, L, Eugenio, P, Fedotov, G, Fegan, S, Filippi, A, Fleming, JA, Fradi, A, Garillon, B, Gilfoyle, GP, Giovanetti, KL, Girod, FX, Goetz, JT, Gohn, W, Golovatch, E, Gothe, RW, Griffioen, KA, Guegan, B, Guidal, M, Guo, L, Hafidi, K, Hakobyan, H, Hanretty, C, Harrison, N, Hattawy, M, Hicks, K, Holtrop, M, Hughes, SM, Hyde, CE, Ilieva, Y, Ireland, DG, Ishkhanov, BS, Jenkins, D, Jiang, H, Jo, HS, Joo, K, Joosten, S, Kalantarians, N, Keller, D, Khandaker, M, Kim, A, Kim, W, Klein, A, Klein, FJ, Koirala, S, Kubarovsky, V, Kuhn, SE, Livingston, K, Lu, HY, Macgregor, IJD, Markov, N, Mattione, P, Mayer, M, McKinnon, B, Mestayer, MD, Meyer, CA, Mirazita, M, Mokeev, V, Montgomery, RA, Moody, CI, Moutarde, H, Movsisyan, A, Camacho, CM, Nadel-Turonski, P, Niccolai, S, Niculescu, G, Osipenko, M, Ostrovidov, AI, Park, K, Pasyuk, E, Peña, C, Pisano, S, Pogorelko, O, Price, JW, Procureur, S, Prok, Y, Protopopescu, D, Puckett, AJR, Ripani, M, Rizzo, A, Rosner, G, Rossi, P, Roy, P, Sabatié, F, Salgado, C, Schott, D, Schumacher, RA, Seder, E, Sharabian, YG, Simonyan, A, Skorodumina, I, Smith, ES, Smith, GD, Sober, DI, Sokhan, D, Sparveris, N, Stepanyan, S, Stoler, P, Strauch, S, Sytnik, V, Taiuti, M, Tian, Y, Trivedi, A, Ungaro, M, Voskanyan, H, Voutier, E, Walford, NK, Watts, DP, Wei, X, Wood, MH, Zachariou, N, Zana, L, Zhang, J, Zhao, ZW & Zonta, I 2015, 'Towards a resolution of the proton form factor problem: New electron and positron scattering data', Physical Review Letters, vol. 114, no. 6, 062003. https://doi.org/10.1103/PhysRevLett.114.062003

TY - JOUR

T1 - Towards a resolution of the proton form factor problem

T2 - New electron and positron scattering data

AU - Adikaram, D.

AU - Rimal, D.

AU - Weinstein, L. B.

AU - Raue, B.

AU - Khetarpal, P.

AU - Bennett, R. P.

AU - Arrington, J.

AU - Brooks, W. K.

AU - Adhikari, K. P.

AU - Afanasev, A. V.

AU - Amaryan, M. J.

AU - Anderson, M. D.

AU - Anefalos Pereira, S.

AU - Avakian, H.

AU - Ball, J.

AU - Battaglieri, M.

AU - Bedlinskiy, I.

AU - Biselli, A. S.

AU - Bono, J.

AU - Boiarinov, S.

AU - Briscoe, W. J.

AU - Burkert, V. D.

AU - Carman, D. S.

AU - Careccia, S.

AU - Celentano, A.

AU - Chandavar, S.

AU - Charles, G.

AU - Colaneri, L.

AU - Cole, P. L.

AU - Contalbrigo, M.

AU - Crede, V.

AU - D'Angelo, A.

AU - Dashyan, N.

AU - De Vita, R.

AU - De Sanctis, E.

AU - Deur, A.

AU - Djalali, C.

AU - Dodge, G. E.

AU - Dupre, R.

AU - Egiyan, H.

AU - El Alaoui, A.

AU - El Fassi, L.

AU - Elouadrhiri, L.

AU - Eugenio, P.

AU - Fedotov, G.

AU - Fegan, S.

AU - Filippi, A.

AU - Fleming, J. A.

AU - Fradi, A.

AU - Garillon, B.

AU - Gilfoyle, G. P.

AU - Giovanetti, K. L.

AU - Girod, F. X.

AU - Goetz, J. T.

AU - Gohn, W.

AU - Golovatch, E.

AU - Gothe, R. W.

AU - Griffioen, K. A.

AU - Guegan, B.

AU - Guidal, M.

AU - Guo, L.

AU - Hafidi, K.

AU - Hakobyan, H.

AU - Hanretty, C.

AU - Harrison, N.

AU - Hattawy, M.

AU - Hicks, K.

AU - Holtrop, M.

AU - Hughes, S. M.

AU - Hyde, C. E.

AU - Ilieva, Y.

AU - Ireland, D. G.

AU - Ishkhanov, B. S.

AU - Jenkins, D.

AU - Jiang, H.

AU - Jo, H. S.

AU - Joo, K.

AU - Joosten, S.

AU - Kalantarians, N.

AU - Keller, D.

AU - Khandaker, M.

AU - Kim, A.

AU - Kim, W.

AU - Klein, A.

AU - Klein, F. J.

AU - Koirala, S.

AU - Kubarovsky, V.

AU - Kuhn, S. E.

AU - Livingston, K.

AU - Lu, H. Y.

AU - Macgregor, I. J.D.

AU - Markov, N.

AU - Mattione, P.

AU - Mayer, M.

AU - McKinnon, B.

AU - Mestayer, M. D.

AU - Meyer, C. A.

AU - Mirazita, M.

AU - Mokeev, V.

AU - Montgomery, R. A.

AU - Moody, C. I.

AU - Moutarde, H.

AU - Movsisyan, A.

AU - Camacho, C. Munoz

AU - Nadel-Turonski, P.

AU - Niccolai, S.

AU - Niculescu, G.

AU - Osipenko, M.

AU - Ostrovidov, A. I.

AU - Park, K.

AU - Pasyuk, E.

AU - Peña, C.

AU - Pisano, S.

AU - Pogorelko, O.

AU - Price, J. W.

AU - Procureur, S.

AU - Prok, Y.

AU - Protopopescu, D.

AU - Puckett, A. J.R.

AU - Ripani, M.

AU - Rizzo, A.

AU - Rosner, G.

AU - Rossi, P.

AU - Roy, P.

AU - Sabatié, F.

AU - Salgado, C.

AU - Schott, D.

AU - Schumacher, R. A.

AU - Seder, E.

AU - Sharabian, Y. G.

AU - Simonyan, A.

AU - Skorodumina, I.

AU - Smith, E. S.

AU - Smith, G. D.

AU - Sober, D. I.

AU - Sokhan, D.

AU - Sparveris, N.

AU - Stepanyan, S.

AU - Stoler, P.

AU - Strauch, S.

AU - Sytnik, V.

AU - Taiuti, M.

AU - Tian, Ye

AU - Trivedi, A.

AU - Ungaro, M.

AU - Voskanyan, H.

AU - Voutier, E.

AU - Walford, N. K.

AU - Watts, D. P.

AU - Wei, X.

AU - Wood, M. H.

AU - Zachariou, N.

AU - Zana, L.

AU - Zhang, J.

AU - Zhao, Z. W.

AU - Zonta, I.

PY - 2015/2/10

Y1 - 2015/2/10

N2 - There is a significant discrepancy between the values of the proton electric form factor, GEp, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GEp from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization and momentum transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing at Q2=1.45GeV2. This measurement is consistent with the size of the form factor discrepancy at Q2≈1.75GeV2 and with hadronic calculations including nucleon and Δ intermediate states, which have been shown to resolve the discrepancy up to 2-3GeV2.

AB - There is a significant discrepancy between the values of the proton electric form factor, GEp, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GEp from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization and momentum transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing at Q2=1.45GeV2. This measurement is consistent with the size of the form factor discrepancy at Q2≈1.75GeV2 and with hadronic calculations including nucleon and Δ intermediate states, which have been shown to resolve the discrepancy up to 2-3GeV2.

UR - http://www.scopus.com/inward/record.url?scp=84922824059&partnerID=8YFLogxK

U2 - 10.1103/PhysRevLett.114.062003

DO - 10.1103/PhysRevLett.114.062003

M3 - Article

AN - SCOPUS:84922824059

SN - 0031-9007

VL - 114

JO - Physical Review Letters

JF - Physical Review Letters

IS - 6

M1 - 062003

ER -

Towards a resolution of the proton form factor problem: New electron and positron scattering data

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