Speaker
Description
The effective number of neutrinos, $N_{\rm eff}$, is an important parameter in standard hot big bang cosmology. In this work, we compute the dominant QED correction to the neutrino-electron interaction rate in the vicinity of neutrino decoupling in the early universe, and estimate its impact on $N_{\rm eff}$. We find that the correction to the interaction rate is at the sub-percent level. The fractional change in $N_{\rm eff}$ due to the rate correction is of order $10^{-5}$ or below, i.e., about a factor of 30 smaller than that recently claimed by Cielo et al., and below the nominal computational uncertainties of the current benchmark value of $N_{\rm eff}$ = 3.0440 ± 0.0002. We therefore conclude that aforementioned number remains to be the state-of-the-art benchmark for $N_{\rm eff}$ in the standard model of particle physics.
Based on arXiv:2402.18481
