Samples from Planck TT,TE,EE+lowE chains in the ∑m_ν–H₀ plane, colour-coded by σ₈. Solid black contours show the constraints from Planck TT,TE,EE+lowE+lensing, while dashed blue lines show the joint constraint from Planck TT,TE,EE+lowE+lensing+BAO, and the dashed green lines additionally marginalize over N_eff. The grey band on the left shows the region with ∑m_ν <  0.056 eV ruled out by neutrino oscillation experiments. Mass splittings observed in neutrino oscillation experiments also imply that the region left of the dotted vertical line can only be a normal hierarchy (NH), while the region to the right could be either the normal hierarchy or an inverted hierarchy (IH).