$N_{\mathrm{eff}}$ in low-scale seesaw models versus the lightest neutrino mass

P. Hernandez, M. Kekic, J. Lopez-Pavon

We evaluate the contribution to $N_{\mathrm{eff}}$ of the extra sterile states in low-scale Type I seesaw models (with three extra sterile states). We explore the full parameter space a…