Stars as Laboratories for Fundamental Physics - MPP Theory Group

Radiative Particle Decays 479
Table 12.2. Neutrino radiative lifetime limits a from SN 1987A.
Area b Boundaries c Radiative lifetime Transition moment d
limit c
µ eff /µ B
1 m ν < 40 τ γ m −1
ν > 0.8×10 15 1.5×10 −8 m −2
ν
3×10 5 < τ tot m −1
ν
2 40 < m ν < 200 τ γ m −1
ν > 0.2×10 15 0.8×10 −8 m −2
ν
3×10 5 < τ tot m −1
ν
3 200 < m ν < 10 7 τ γ m ν > 7×10 18 1.6×10 −10 m −1
ν
9×10 9 < τ tot m ν
4 m ν < 10 7 B γ < 1.2×10 −9 1.4×10 −5 m −3/2
ν τ −1/2
tot
4×10 8 < τ tot m ν < 9×10 9
10 −5 < τ tot m −1
ν < 3×10 5
5 m ν < 10 7 B γ < 3×10 −10 0.7×10 −5 m −3/2
ν τ −1/2
tot
τ tot m ν < 4×10 8
10 −5 < τ tot m −1
ν < 3×10 5
6 τ tot m −1
ν < 10 −5 B γ < 0.01 —
a For the anisotropy parameter α = −1.
b Numbered as in Fig. 12.16.
c Neutrino masses in eV, lifetimes in s.
d Upper limit.
trinos have Dirac masses and thus right-handed partners which could
be emitted from the inner core of the SN by helicity-flipping processes
(Sect. 13.8). Moreover, entirely new particles could be produced and
escape from there.
The present bounds can be scaled to such cases if one calculates the
total energy E x,tot = f x 10 53 erg emitted in the new x particles, where
1×10 53 erg is the total energy that was used for a standard ν plus ν.
Self-consistency requires f x < 1, of course. In addition, one needs the
average energy ⟨E x ⟩ of the new objects which allows one to define an
approximate equivalent temperature T x = 1 3 ⟨E x⟩. Depending on the x
mass and total lifetime one can then read the radiative lifetime limits
directly from Figs. 12.8, 12.9, and 12.14, except that they must be
relaxed by a factor f x for the reduced fluence.