Speaker
Dasuni Adikaram
(Jefferson Lab)
Description
There is a significant discrepancy between the values of the proton electric form factor, $G^p_E$, extracted using unpolarized and polarized electron scattering. Calculations predict that small two photon exchange (TPE) contributions can significantly affect the extraction of $G^p_E$ from the un-polarized 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. We present the cross section ratios measured at $Q^2 = 1.45$ GeV$^2$ and at $\epsilon = 0. 88$ along with the estimations of systematic uncertainties. A detailed comparison of new results with previous measurements and theoretical calculations will also be presented.
Primary authors
Brian Raue
(Florida International University)
Dasuni Adikaram
(Jefferson Lab)
Dipak Rimal
(University of Florida)
John Arrington
(Argonne National Laboratory)
Larry Weinstein
(Old Dominion University)
Will Brooks
(Universidad Técnica Federico Santa María)
