X17 discovery potential in the $\gamma N\to e^{+}{e}^{-}N$ process at electron scattering facilities

Abstract

We propose a direct search for the X17 particle, which was conjectured to explain the ATOMKI ${}^8$Be and ${}^4$He anomalies, through the dilepton photoproduction process on a nucleon in the photon energy range below or around the pion production threshold. For the scenarios of either pseudoscalar, vector, or axial-vector quantum numbers of the conjectured X17, we use existing constraints to estimate the X17 signal process. For dilepton resolutions which have been achieved in previous experiments, a signal-to-background ratio of up to an order of magnitude is found for a neutron target, and in particular for the pseudoscalar and vector X17 scenarios.

Comments: 5 pages, 2 figures