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
,
J. Ball
(1)
,
M. Battaglieri
,
I. Bedlinskiy
,
A. S. Biselli
,
J. Bono
,
S. Boiarinov
,
W. J. Briscoe
,
V. D. Burkert
,
D. S. Carman
,
A. Celentano
,
S. Chandavar
,
G. Charles
(1)
,
L. Colaneri
,
P. L. Cole
,
M. Contalbrigo
,
A. d'Angelo
,
N. Dashyan
,
R. de Vita
,
E. de Sanctis
,
A. Deur
,
C. Djalali
,
G. E. Dodge
,
R. Dupre
(2)
,
H. Egiyan
,
A. El Alaoui
,
L. El Fassi
,
P. Eugenio
,
G. Fedotov
,
S. Fegan
,
A. Filippi
,
J. A. Fleming
,
A. Fradi
,
G. P. Gilfoyle
,
K. L. Giovanetti
,
F. X. Girod
,
J. T. Goetz
,
W. Gohn
,
E. Golovatch
,
R. W. Gothe
,
K. A. Griffioen
,
M. Guidal
(2)
,
L. Guo
,
K. Hafidi
,
H. Hakobyan
,
N. Harrison
,
M. Hattawy
(2)
,
K. Hicks
,
M. Holtrop
,
S. M. Hughes
,
C. E. Hyde
,
Y. Ilieva
,
D. G. Ireland
,
B. S. Ishkhanov
,
D. Jenkins
,
H. Jiang
,
K. Joo
,
S. Joosten
,
M. Khandaker
,
W. Kim
,
A. Klein
,
F. J. Klein
,
S. Koirala
,
V. Kubarovsky
,
S. E. Kuhn
,
H. Y. Lu
,
I . J . D. Macgregor
,
N. Markov
,
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. Muñoz Camacho
(2)
,
P. Nadel-Turonski
,
S. Niccolai
(2)
,
G. Niculescu
,
M. Osipenko
,
A. I. Ostrovidov
,
K. Park
,
E. Pasyuk
,
S. Pisano
(2)
,
O. Pogorelko
,
S. Procureur
(1)
,
Y. Prok
,
D. Protopopescu
,
A. J. R. Puckett
,
M. Ripani
,
A. Rizzo
,
G. Rosner
,
P. Rossi
,
F. Sabatié
(1)
,
D. Schott
,
R. A. Schumacher
,
Y. G. Sharabian
,
A. Simonyan
,
I. Skorodumina
,
E. S. Smith
,
G. D. Smith
,
D. I. Sober
,
N. Sparveris
,
S. Stepanyan
,
S. Strauch
,
V. Sytnik
,
M. Taiuti
,
Ye Tian
,
A. Trivedi
,
M. Ungaro
,
H. Voskanyan
,
E. Voutier
(3)
,
N. K. Walford
,
D. P. Watts
,
X. Wei
,
M. H. Wood
,
N. Zachariou
,
L. Zana
,
J. Zhang
,
Z. W. Zhao
,
I. Zonta
D. Adikaram
- Function : Author
D. Rimal
- Function : Author
L. B. Weinstein
- Function : Author
B. Raue
- Function : Author
P. Khetarpal
- Function : Author
R. P. Bennett
- Function : Author
J. Arrington
- Function : Author
W. K. Brooks
- Function : Author
K. P. Adhikari
- Function : Author
A. V. Afanasev
- Function : Author
M. J. Amaryan
- Function : Author
M. D. Anderson
- Function : Author
M. Battaglieri
- Function : Author
I. Bedlinskiy
- Function : Author
- PersonId : 755548
- ORCID : 0000-0002-0289-0866
A. S. Biselli
- Function : Author
J. Bono
- Function : Author
S. Boiarinov
- Function : Author
W. J. Briscoe
- Function : Author
V. D. Burkert
- Function : Author
D. S. Carman
- Function : Author
A. Celentano
- Function : Author
- PersonId : 764982
- ORCID : 0000-0002-7104-2983
S. Chandavar
- Function : Author
L. Colaneri
- Function : Author
P. L. Cole
- Function : Author
M. Contalbrigo
- Function : Author
A. d'Angelo
- Function : Author
- PersonId : 755183
- ORCID : 0000-0003-3050-4907
N. Dashyan
- Function : Author
R. de Vita
- Function : Author
E. de Sanctis
- Function : Author
A. Deur
- Function : Author
- PersonId : 755225
- ORCID : 0000-0002-2203-7723
C. Djalali
- Function : Author
G. E. Dodge
- Function : Author
R. Dupre
- Function : Author
- PersonId : 740338
- IdHAL : raphael-dupre
- ORCID : 0000-0001-7935-8221
- IdRef : 165334010
H. Egiyan
- Function : Author
- PersonId : 755392
- ORCID : 0000-0002-5881-3616
A. El Alaoui
- Function : Author
L. El Fassi
- Function : Author
P. Eugenio
- Function : Author
G. Fedotov
- Function : Author
S. Fegan
- Function : Author
A. Filippi
- Function : Author
J. A. Fleming
- Function : Author
A. Fradi
- Function : Author
G. P. Gilfoyle
- Function : Author
K. L. Giovanetti
- Function : Author
F. X. Girod
- Function : Author
J. T. Goetz
- Function : Author
W. Gohn
- Function : Author
E. Golovatch
- Function : Author
R. W. Gothe
- Function : Author
K. A. Griffioen
- Function : Author
L. Guo
- Function : Author
K. Hafidi
- Function : Author
H. Hakobyan
- Function : Author
N. Harrison
- Function : Author
K. Hicks
- Function : Author
M. Holtrop
- Function : Author
- PersonId : 755237
- ORCID : 0000-0002-1110-1152
S. M. Hughes
- Function : Author
C. E. Hyde
- Function : Author
Y. Ilieva
- Function : Author
D. G. Ireland
- Function : Author
B. S. Ishkhanov
- Function : Author
D. Jenkins
- Function : Author
H. Jiang
- Function : Author
K. Joo
- Function : Author
S. Joosten
- Function : Author
- PersonId : 769647
- ORCID : 0000-0003-4947-877X
M. Khandaker
- Function : Author
- PersonId : 755252
- ORCID : 0000-0003-0370-9536
W. Kim
- Function : Author
A. Klein
- Function : Author
F. J. Klein
- Function : Author
S. Koirala
- Function : Author
V. Kubarovsky
- Function : Author
S. E. Kuhn
- Function : Author
H. Y. Lu
- Function : Author
I . J . D. Macgregor
- Function : Author
N. Markov
- Function : Author
M. Mayer
- Function : Author
B. Mckinnon
- Function : Author
M. D. Mestayer
- Function : Author
C. A. Meyer
- Function : Author
M. Mirazita
- Function : Author
V. Mokeev
- Function : Author
- PersonId : 755398
- ORCID : 0000-0002-4557-1320
R. A. Montgomery
- Function : Author
C. I. Moody
- Function : Author
H. Moutarde
- Function : Author
A Movsisyan
- Function : Author
C. Muñoz Camacho
- Function : Author
- PersonId : 742360
- IdHAL : carlos-munoz-camacho
P. Nadel-Turonski
- Function : Author
G. Niculescu
- Function : Author
M. Osipenko
- Function : Author
- PersonId : 755399
- ORCID : 0000-0001-9618-3013
A. I. Ostrovidov
- Function : Author
K. Park
- Function : Author
E. Pasyuk
- Function : Author
- PersonId : 755395
- ORCID : 0000-0003-3877-1815
O. Pogorelko
- Function : Author
Y. Prok
- Function : Author
D. Protopopescu
- Function : Author
- PersonId : 755397
- ORCID : 0000-0002-8047-6513
A. J. R. Puckett
- Function : Author
M. Ripani
- Function : Author
- PersonId : 755184
- ORCID : 0000-0001-8632-7538
A. Rizzo
- Function : Author
G. Rosner
- Function : Author
P. Rossi
- Function : Author
D. Schott
- Function : Author
R. A. Schumacher
- Function : Author
Y. G. Sharabian
- Function : Author
A. Simonyan
- Function : Author
I. Skorodumina
- Function : Author
E. S. Smith
- Function : Author
G. D. Smith
- Function : Author
D. I. Sober
- Function : Author
N. Sparveris
- Function : Author
- PersonId : 768156
- ORCID : 0000-0002-6278-1178
S. Stepanyan
- Function : Author
S. Strauch
- Function : Author
V. Sytnik
- Function : Author
M. Taiuti
- Function : Author
Ye Tian
- Function : Author
- PersonId : 766352
- ORCID : 0000-0003-0545-942X
A. Trivedi
- Function : Author
M. Ungaro
- Function : Author
H. Voskanyan
- Function : Author
E. Voutier
- Function : Author
- PersonId : 749688
- IdHAL : eric-voutier
- ORCID : 0000-0003-4990-3369
- IdRef : 081534604
N. K. Walford
- Function : Author
D. P. Watts
- Function : Author
X. Wei
- Function : Author
M. H. Wood
- Function : Author
N. Zachariou
- Function : Author
- PersonId : 760627
- ORCID : 0000-0001-7621-5612
L. Zana
- Function : Author
- PersonId : 755516
- ORCID : 0000-0002-1434-052X
J. Zhang
- Function : Author
Z. W. Zhao
- Function : Author
I. Zonta
- Function : Author
Abstract
There is a significant discrepancy between the values of the proton electric form factor, $G_E^p$, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of $G_E^p$ 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 ($\varepsilon$) and momentum transfer ($Q^2$) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing $\varepsilon$ at $Q^2 = 1.45 \text{ GeV}^2$. This measurement is consistent with the size of the form factor discrepancy at $Q^2\approx 1.75$ GeV$^2$ and with hadronic calculations including nucleon and $\Delta$ intermediate states, which have been shown to resolve the discrepancy up to $2-3$ GeV$^2$.
Domains
Nuclear Experiment [nucl-ex]Origin | Files produced by the author(s) |
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