Advances in High Energy Physics / 2013 / Article / Fig 1

Review Article

Heavy Chiral Fermions and Dark Matter

Figure 1

Relative relic density of stable fourth-generation neutrino as a function of its mass for mixing angle values (solid), (dashed), (dotted), and (dot-dashed). The shaded region is excluded by LEP-2 data [1] in the case of being a Dirac fermion. Plot from [10].