1. Lecture 3 – neutrino oscillations and hadrons
Review of leptons
Neutrino oscillations
Introduction to hadrons
FK7003

2. The lepton family Charge (e) Mass (GeV) e- (e+) -1 (+1) 0.0005 ne,(ne)
Spin 1/2
Lepton (antilepton)
Charge (e)
Mass (GeV)
e- (e+)
-1 (+1)
0.0005
ne,(ne) 0
m- (m+)
0.105
nm (nm)
t- (t+)
1.8
nt (nt)
6 leptons + antileptons.
Divided into 3 families/flavours/multipletes: electron,muon tau
FK7003

3. Lepton interactions e- m- m- e- e- nm m+W- g nm m+
Charged leptons interact via the em and weak forces.
Neutrinos only interact via the weak force.
Lepton number is always conserved at a vertex and in the whole process.
As for all forces:
Charge conservation and energy-momentum
conservation for incoming and outgoing particles.
Charge is conserved at a vertex though energy can appear to be
violated when dealing with ”internal lines” (lecture 1).
FK7003

4. Neutrino masses Mass (MeV) ne < 0.0003 nm <0.2 nt <18 Lepton
FK7003

5. Neutrino oscillationsm+ p+
Conserves Lm nm
Conserves Lt nt t-
Whole process violates: Lm, Lt
FK7003

6. Neutrino oscillation formalism
FK7003

7. Real(ni)
Real(ni)
Real(na)
FK7003
nb probability L
na prob.
na prob.

8. Neutrino Interactions in Matterl I0
I(x)
103
106
109 n
Neutrino interaction lengthi In water/km x
 interaction 1
103
106
E  (TeV)
Probability of interaction ~ 10-5 / km water at 100 TeV energy
100 billion neutrinos pass through your thumbnail each second but only
1-2 will interact in your body during your lifetime.
FK7003

9. Neutrinos arriving at Earth – not for the exam
Relevant for
this lecture
relics from Big Bang
nuclear reactions in Sun
explosions of supernova
Flux/energy (cm-2s-1MeV-1)
natural radioactive decay in Earth
nuclear reactors
remnants of supernova
interactions of cosmic rays
in atmosphere
Active Galactic Nuclei
Neutrino energy (eV)
FK7003

10. Atmospheric neutrinos and Super Kamiokande
Boat
FK7003

11. Super-K: nm oscillations
From above
15 km
Super-K
no oscillations
P(nm nm ) (Data/Prediction for oscillations)
oscillations
Earth
From below
13000 km
FK7003

12. Atmospheric neutrino results
E=1 GeV
FK7003

13. Neutrinos arriving at Earth – not for the exam
Relevant for
this lecture
relics from Big Bang
nuclear reactions in Sun
explosions of supernova
Flux/energy (cm-2s-1MeV-1)
natural radioactive decay in Earth
nuclear reactors
remnants of supernova
interactions of cosmic rays
in atmosphere
Active Galactic Nuclei
Neutrino energy (eV)
FK7003

14. Neutrinos in the sun – not for the exam
Fusion process leading to aa
kne measured flux on earth can be predicted
Solar neutrino energies
FK7003

15. Solar neutrino problem
FK7003

16. SNO
FK7003

17. Results
FK7003

18. Generalise for 3 neutrinos
FK7003

19. Mass2
(eV2)
0.003
Flavour composition
of mass state.
0.0001
FK7003

20. Question
FK7003

21. Question
FK7003

22. Question
FK7003

23. Summary of neutrino oscillations
Neutrinos produced in the weak force are flavour eigenstates but not mass eigenstates.
Neutrino oscillations between flavours occur as a consequence of non-zero mixing angles and a non- zero difference between the mass states
Experiments on atmospheric and solar neutrinos demonstrate neutrino oscillations.
FK7003