Planck 2σ = 0.36 ∆Neff = 0.24 - Familons
2 × 10−1
∆Neff = 0.16 - Majorons
∆Neff
∆Neff = 0.12 - TF = TQCD SM minimum w. spin
1 × 10−1
∆Neff = 0.089 - DM-nucleon mediators ∆Neff = 0.071 - TF = TQCD SM minimum
5 × 10−2
CMB-S4 2σ = 0.054 ∆Neff = 0.046 - TF < TR SM minimum w. spin ∆Neff = 0.034 - SM min. w. one massive scalar ∆Neff = 0.027 - TF < TR SM minimum
2 × 10−2
credit: Daniel Green
