Constraints on the dark photon from deep inelastic scattering

We investigate constraints on the dark photon arising from an analysis of deep inelastic scattering (DIS) data. We perform extractions of parton distribution functions (PDFs) with and without a dark photon being present and allow the dark photon mixing parameter and mass to vary. We also include the effects of vector meson dominance to ensure the correct photo-production limit. By considering the variation of the total $\chi^2$ arising from such extractions we infer exclusion limits on the kinetic mixing parameter of the dark photon for dark photon mass up to $80\ {\rm GeV}$.