Vacuum-Polarization Corrections to Solar-Fusion Rates

The vacuum-polarization corrections to rates for nuclear-fusion reactions in the $pp$ chain and in the CNO cycle are calculated. For the reactions of particular importance to the solar-neutrino problem, the $\text{Hethree}$, $\text{Hefour}$, $\text{Be}$, and $\text{Ni}$ reactions, we find the magnitude of the effect to be less than 2%. The effect of VP on all the other reaction rates is expected to be of a similar order of magnitude. We discuss how these results affect the predicted fluxes of solar neutrinos.