Very First Measurement of the Two-Photon Exchange Contribution to the Elastic Electron-Neutron Scattering Cross Section using BigBite and Super BigBite Spectrometers in Jefferson Lab's Hall A

The electromagnetic form factors of the nucleon can be measured experimentally either by using the polarization transfer technique or by using the Rosenbluth technique. Experimental data have shown that the values of the ratio of proton Sachs form factors, $G^{p}_{E}/G^{p}_{M}$, obtained using these two methods have significant discrepancy. This inconsistency is believed to be due to the two-photon exchange (TPE) contribution to the $e-N$ elastic scattering process. The contribution of TPE increases with increasing $Q^2$ and for the case of neutron it has been pedicted to reach about $30\%$ of the Rosenbluth slope value at $Q^{2}=5\,\text{(GeV/c)}^2$. Hence, the precise assessment of the impact of TPE in elastic $e-N$ scattering is extremely important for the better understanding of the nucleon form factors. This effect has been studied extensively for $e-p$ scattering but has never been examined experimentally for $e-n$ scattering. In this talk, I will present an overview of one of the currently approved experiments to measure TPE contribution to the $e-n$ elastic scattering cross section with high precision, using the new Super BigBite Spectrometer (SBS) and the upgraded BigBite Spectrometer in JLab's experimental Hall A.