Etudes des proprietes des neutrinos dans les contextes ...

tel-00450051, version 1 - 25 Jan 2010
600
400
200
0
200
0
sub-GeV e-like sub-GeV µ-like
multi-GeV e-like
-0.8 -0.4 0
cosΘ
0.4 0.8
multi-GeV µ-like + PC
-0.8 -0.4 0
cosΘ
0.4 0.8
Figure 2.5: Zenith angle distributions for sub-GeV and multi-GeV e-like and µ-like
events at SK. The bars show the (no-oscillations) Monte Carlo predictions; the lines
show the predictions for νµ ↔ ντ oscillations with the best-fit parameters ∆m 2 =
3.5 × 10 −3 eV 2 , sin 2 2θ = 1.0. From [106].
Interpretation of the experimental data
The measurements of the double ratio R(µ/e) for contained events at Super-K
(848 live days) give
R = 0.68 ± 0.02 (stat.) ± 0.05 (syst.) (sub-GeV), (2.10)
for sub-GeV events which were fully contained in the detector and
R = 0.68 ± 0.04 (stat.) ± 0.08 (syst.) (multi-GeV) . (2.11)
for fully- and partially-contained multi-GeV events. The value of R for sub-GeV
events is different from unity (to which it should be equal in no-oscillation case)
by 5.9σ. The SK Collaboration subdivided their atmospheric neutrino events
into several groups, depending on the energy of the charged leptons produced.
Fully contained (FC) events are those for which the neutrino interaction vertex
is located inside the detector and all final state particles do not get out of it.
FC events are further subdivided into sub-GeV (visible energy < 1.33 GeV) and
multi-GeV (visible energy > 1.33 GeV) events. Partially contained (PC) events
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