Heavy Chiral Fermions and Dark Matter

Figure 3

Relic density of stable fourth-generation neutrino 𝜒 as a function of its mass for 𝑀_𝑍′=400GeV (dashed) and 800 GeV (solid) with a coupling constant 𝑔_𝑋=0.3. The green band represents the observed DM density. Plot from [11].