Constraints on the dark sector from electroweak precision observables

We revisit the Standard Model fit to electroweak precision observables using the latest data and the Particle Data Group value of the mass of the W boson. This analysis is repeated for the value reported by CDF. The constraints on the parameter space for dark photons arising from these electroweak precision observables are then evaluated for both values of the W boson mass. We also extend previous work by placing the first electroweak precision observable constraints on the coupling of dark photons to the fermionic dark matter sector.