Primordial Helium Production in a Charged Universe

Abstract

We use the constraints arising from primordial nucleosynthesis to bound a putative electric charge density $|e|n_q$ of the universe. We find $|n_q/n_γ| \lesssim 10^{-43}$, four orders of magnitude more stringent than previous limits. We also work out the bounds on $n_q$ in models with a photon mass, that allows to have a charge density without large-scale electric fields.