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

TL;DR

This paper predicts the ratio of positron-proton to electron-proton elastic scattering cross sections using a global fit that includes two-photon exchange corrections, indicating measurable deviations from unity in upcoming experiments.

Contribution

The paper provides the first comprehensive prediction of the cross section ratio incorporating two-photon exchange effects based on a global fit of elastic $ep$ data.

Findings

Predicted cross section ratios deviate from unity by more than 3σ in upcoming experiments.

Inclusion of two-photon exchange corrections is crucial for accurate predictions.

Predictions cover kinematic regions of VEPP-3 and JLab experiments.

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 $3\sigma$.