The ratio of $e^{\pm }p$ scattering cross sections predicted from the global fit of elastic $ep$ data

Abstract

We present predictions for the value of the cross section ratio $\sigma (e^{+}p\to e^{+}p)/\sigma (e^{-}p\to e^{-}p)$, determined from our fit of the elastic $ep$ cross section and polarization data. In this fit we took into account the phenomenological two-photon exchange dispersive correction. The cross section ratios which are expected to be measured by the VEPP-3 experiment are computed. The kinematical region which will be covered by the E04-116 JLab experiment is also considered. It is shown that for both experiments the predicted cross section ratios deviate from unity within more than $3\sigma$.

Comments: 7 pages, 4 figures