DEMNUni-Cov power spectrum. Top: The solid and dashed lines represents the mean DEMNUni-Cov power spectrum, for three snapshots and the two cosmologies 0ν and 16ν. The corresponding shaded regions show the dispersion over the 50 realisations. The black short dashed line is the shot-noise level for the 1024³ CDM particles. Bottom: Ratio between the mean power spectrum of the massive neutrino cosmology and the mass-less one. The grey area represents the dispersion over the 50 realisations at z = 0.