We proposed that parity-violating electron scattering (PVES) offers a powerful tool to probe the hypothetical dark photon. We calculated the dark photon contributions to PVES asymmetries in both elastic and deep-inelastic scattering (DIS). These contributions are characterised by the corrections to the standard model couplings C₁ₐ, \, C₂ₐ, and C₃ₐ. At low scales, the corrections to C₁ₐ and C₃ₐ could be as large as 5\% were a dark photon to exist. In DIS at very high Q², of relevance to HERA or the EIC, the dark photon could induce substantial corrections to C₂ₐ, suggesting as large as 10\% uncertainties in the extraction of valence parton distribution functions. We also extracted the favoured regions of the dark photon parameter space by fitting the parity violation data and the CDF W boson mass, which prefer a heavy dark photon with mass above the Z-boson mass.
Thomas et al. (Mon,) studied this question.