Etudes des proprietes des neutrinos dans les contextes ...

tel-00450051, version 1 - 25 Jan 2010
Probability
1
0.5
P(ν e -> ν e )
P(ν µ -> ν e )
P(ν τ -> ν e )
0
0 5 10 15
distance ( r/100 Km )
Probability
1
0.5
0
0 5 10 15
distance ( r/100 Km )
Figure 5.10: Neutrino (left) and antineutrino (right) oscillation probabilities in
three flavours, as a function of the distance from the neutron-star surface (10
km), including the neutrino-neutrino interaction and Vµτ refractive index. The
different curves correspond to electron (anti)neutrinos (dot-dashed), muon (solid)
and tau (dashed) (anti)neutrinos. The results are obtained solving the evolution
equations numerically for a neutrino energy of 5 MeV as an example. The case
of inverted hierarchy and small neutrino mixing angle θ13 is shown where the
neutrino self-interaction effects are particularly impressive : the regimes of synchronized
and bipolar oscillations can be recognized in the first 100 km. In the
case of the electron neutrinos (left figure), the spectral split is also apparent.
neutrino interaction. We have first checked it by observing the typical features
just described and reproduced the 2 flavour results of Ref. [52]. In this paper, the
density is lower than the one used in our previous work. Indeed, it was difficult
to identify clearly the different regimes, since the MSW resonances occured in
the same region where the self-interactions are important. For instance, this
implies that a spectral split occurs in normal hierarchy as well. Note that the
results of Ref. [52], for the same reasons, have created a lot of confusion in the
international community. In reality, the regimes described in section 5.2 become
well identified when a more realistic density profile is used, as shown by following
works [58]. Since we are interested in the consequences of the δ phase on the
fluxes, we have developed a 3 flavour code.This has been one of the very first 3
flavour simulations including Hνν. To check it, we reproduced the results of [61].
In the following figures, we present the numerical results we obtained showing
the typical non-linear behaviour of neutrinos in a supernova environment: the
synchronization regime, the bipolar regime, and the spectral splits. As we explore
in chapters 6 and 7, these features have an impact on the CP-violating phase
effects and on the fluxes on Earth depending on the hierarchy and if θ13 is zero
or not. Figure 5.10 presents the (anti)neutrino oscillation probabilities within
the star. One recognizes the synchronized regime in the first 50 km outside the
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