Heavy sterile neutrinos - MPP Theory Group

A.D. Dolgov et al. / Nuclear Physics B 590 (2000) 562–574 569
Fig. 2. Maximum lifetime of sterile neutrino, allowed by BBN, as a function of the heavy neutrino
mass, both for an optimistic bound, N = 0.2, and for a conservative bound, N = 1.0. The upper
panel corresponds to ν µ ↔ ν s or ν τ ↔ ν s mixings, while the lower one to ν e ↔ ν s mixing.
Table 1
Fitting parameters for minimum allowed mixing (sin 2 θ) min fitted by Eq. (18) and maximum allowed
life-time τ max fitted by Eq. (19)
Mixing N (sin 2 θ) min fitting parameters τ max fitting parameters
s 1 s 2 α t 1 t 2 β
ν s −ν µ,τ 0.2 1423 −4.99 × 10 −6 −3.727 100.1 0.04788 −1.901
ν s −ν µ,τ 1 568.4 −5.17 × 10 −6 −3.549 128.7 0.04179 −1.828
ν s −ν e 0.2 140.4 −9.9 × 10 −6 −3.222 1218 0.0513 −2.658
ν s −ν e 1 66.33 −1.05 × 10 −5 −3.070 1699 0.0544 −2.652