This item is non-discoverable
Loading...
Non-discoverable
Towards a resolution of the proton form factor problem: New electron and positron scattering data
Adikaram, D Rimal, D Weinstein, LB Raue, B Khetarpal, P Bennett, RP Arrington, J Brooks, WK Adhikari, KP Afanasev, AV
Adikaram, D
Rimal, D
Weinstein, LB
Raue, B
Khetarpal, P
Bennett, RP
Arrington, J
Brooks, WK
Adhikari, KP
Afanasev, AV
Citations
Altmetric:
Genre
Journal Article
Date
2015-02-10
Advisor
Committee member
Group
Department
Subject
Permanent link to this record
Collections
Research Projects
Organizational Units
Journal Issue
DOI
10.1103/PhysRevLett.114.062003
Abstract
© 2015 American Physical Society. 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.
Description
Citation
Citation to related work
American Physical Society (APS)
Has part
Physical Review Letters
ADA compliance
For Americans with Disabilities Act (ADA) accommodation, including help with reading this content, please contact scholarshare@temple.edu