1. Cosmological/phenomenological implications of neutrino oscillations
Steve King
10/08/2019
S.F.King, NuFact02, London

2. Atmospheric Neutrino Oscillations
10/08/2019
S.F.King, NuFact02, London

3. Solar Neutrino Oscillations
LMA
LOW
Choubey talk

4. I. Cosmological Implications
See e.g. Kainulainen and Olive, hep-ph/
Cosmological relic density and dark matter
Galaxy structure limits on neutrino mass
Neutrinos and nucleosynthesis
Neutrinos and supernova
Neutrinos and cosmic rays
10/08/2019
S.F.King, NuFact02, London

5. Cosmological relic density and dark matter
In the early universe neutrinos were in thermal equilibrium with photons, electrons and positrons. When the universe cooled to temperatures of order 1 MeV the neutrinos decoupled, leading to a present day number density similar to photons. If neutrinos have mass they will contribute to mass density of universe, leading to the constraint corresponding to
From the lab limit on the electron-like neutrino mass together with the atmospheric and solar mass splittings we have a stronger constraint corresponding to the range which implies that neutrinos cannot be the dominant component of dark matter.
10/08/2019
S.F.King, NuFact02, London

6. Galaxy structure limits neutrino mass
Tegmark (opposite), Wang, Zaldarriaga
CMB power spectrum
2dF Galaxy Redshift survey astro-ph/
Galaxy power spectrum
10/08/2019
S.F.King, NuFact02, London

7. Neutrinos and nucleosynthesis
The number of light “neutrino species” (or any light species) affects the freeze-out temperature of weak processes which determine n/p, and successful nucleosynthesis gives a constraint
10/08/2019
S.F.King, NuFact02, London

8. What about sterile neutrinos
What about sterile neutrinos? The limit on applies to them also, but they need to be produced during the time when nucleosynthesis was taking place, and the only way to produce them is via neutrino oscillations. This leads to strong limits on the sterile-active neutrino mixing angles which disfavour LSND – assuming the primordial lepton asymmetry is not anomalously large (Y.Y.Y.Wong et al)
10/08/2019
S.F.King, NuFact02, London

9. Neutrinos and Supernovae
99% of a supernova energy is emitted in neutrinos.
From SN1987A in Small Magellanic Cloud neutrinos were observed. Studying the spread in arrival times over 10 s leads to
LMA affects SN1987A (Valle talk)
However SN have their own problems such as how they explode at all, and how the neutron star remnant is kick-started.
10/08/2019
S.F.King, NuFact02, London

10. Neutrinos and Cosmic Rays
GZK cut-off may be exceeded if UHE neutrinos scatter off relic background nu’s to produce Z’s within 50 Mpc – need nu mass
But recent data from Fly’s Eye, HiRes and Yakutsk strongly suggest (7 sigma) that GZK cut-off is present after all (Bahcall and Waxman hep-ph/ )
Z-burst model
10/08/2019
S.F.King, NuFact02, London

11. II. Phenomenological Implications
Neutrino mass patterns
Neutrino mass matrices
Neutrinoless double beta decay
SUSY and LFV
Highlights of theory talks yesterday in WG1/4
10/08/2019
S.F.King, NuFact02, London

12. Possible three neutrino mass patterns:
“Normal”
“Inverted”
10/08/2019
S.F.King, NuFact02, London

13. Large neutrinoless double beta decay
Successful leading order light Majorana matrices Barbieri,Hall,Smith,Strumia,Weiner;Altarelli,Feruglio;SFK hep-ph/ ;Ross talk
Type A (zero in 11)
Type B (non-zero 11)
Green “natural”
Hierarchy
Large neutrinoless double beta decay
Inverted hierarchy
Pseudo-Dirac
Degenerate
10/08/2019
S.F.King, NuFact02, London

14. Neutrinoless double beta decay
If the electron neutrino is Majorana, then neutrinoless double beta decay
Klapdor-Kleingrothaus et al (2001) have claimed a signal based on re-analysis of Heidelberg-Moscow data:
(Criticised by Aalseth et al, Feruglio et al.)
GENIUS would resolve this problem with sensitivity down to 0.01 eV
Degenerate B:
From Pascoli and Petcov (assume LMA)
Inverted hierarchy B:
Hierarchy and Inverted A:
c.f. KATRIN tritium decay sensitivity

15. This will lead to large 23 lepton flavour violation and
SUSY and LFV
If SUSY is present then neutrino masses inevitably lead to lepton flavour violation due to radiatively generated off-diagonal slepton masses
e.g.
Blazek, SFK
This will lead to large 23 lepton flavour violation and
10/08/2019
S.F.King, NuFact02, London

16. Blazek,SFK

17. WG1/4 talks yesterday Y. Shimizu
MSSM with neutrino masses leads to sizeable LFV. Plots below are for minimal supergravity – in realistic string models even larger rates would be expected due to non-universal A-terms (Ross)
10/08/2019
S.F.King, NuFact02, London

18. In such a scheme BR(deg)<BR(inv)~BR(hier)
N. Shimoyama
In a simplified model where the right-handed neutrino masses are universal the MSSM with neutrino masses leads to too-large rates for with a hierarchical neutrino mass spectrum
In such a scheme BR(deg)<BR(inv)~BR(hier)
M. Koike
He studied
He concluded that Z~30-60 is best for experimental searches, and it is possible to distinguish models of new physics by measurement of several kinds of nuclei.
10/08/2019
S.F.King, NuFact02, London

19. J. Sato
He discussed the possibility that the signal of wrong sign muons in a long baseline experiment may either be due to neutrino oscillations or to some new flavour changing interaction involving neutrinos. Such interactions may be generated in SUSY models, with the mu-tau channel being the most effective leading to an “enhanced oscillation effect” at CNGS.
K. Babu
Proposed an explanation of LSND involving three active neutrinos, but with lepton number violating decay Predicts that MiniBoone sees no oscillation signal since it uses neutrinos from pion decay. Michel parameter rho= (not ¾). Fermi constant from muon decay differs by 0.2%.
10/08/2019
S.F.King, NuFact02, London

20. Final Remarks
Neutrino mass and mixing angles as inferred from oscillations plays a crucial role in cosmology in particular dark matter, galaxy structure, nucleosynthesis, supernovae and cosmic rays.
Superbeams in medium term, and neutrino factory in longer term are required to determine the 13 mixing angle, the CP phase and the pattern of neutrino masses to really pin down our universe.
We also need to know the absolute scale of neutrino mass from neutrinoless double beta decay or tritium beta decay – present best limit is from galaxy structure. GRBs could also provide strong limits in future (Choubey,SFK).
If SUSY is present neutrino masses (via the see-saw mechanism) lead to lepton flavour violation which according to talks at this workshop could be observed soon.
In summary neutrino oscillations not only are the most important discovery in particle physics for 20 years but also have profound cosmological and phenomenological implications.
10/08/2019
S.F.King, NuFact02, London