Dark force detection in low energy e-p collisions

We study the prospects for detecting a light boson X with mass m X ≾ 100 MeV at a low energy electron-proton collider. We focus on the case where X dominantly decays to e + e − as motivated by recent “dark force” models. In order to evade direct and indirect constraints, X must have small couplings to the standard model (α X ≾ 10 −8 ) and a sufficiently large mass ( m X ≳ 10 MeV). By comparing the signal and background cross sections for the e − p e + e − final state, we conclude that dark force detection requires an integrated luminosity of around 1 ab −1 , achievable with a forthcoming JLab proposal.