CONGRATULATIONS - NOBEL PRIZE IN PHYSICS 2016

NEUTRINO OSCILLATIONS & MASS

the fundamental discoveries in physics con4nues F. TASNÁDI

LINKÖPING UNIVERSITY

THEORETICAL PHYSICS

CONGRATULATIONS - NOBEL PRIZE IN PHYSICS 2016

2

… the secrets of exotic matter

David J. Thouless

F. Duncan M. Haldane J. Michael Kosterlitz

/quantum physics becomes visible in the cold/

ONE WAY OF DOING FUNDAMENTAL PHYSICS

Higgs boson the

“God particle”

125 GeV 4 July 2012

LHC

STANDARD MODEL

27 KM

4

ANOTHER WAY OF DOING FUNDAMENTAL PHYSICS

supersymmetry

bosons fermions

SUSY

(super)string theory

PARTICLE WORLD - THE STANDARD MODEL

neutrinos

flavours

/1970 - ???/

METAMORPHOSIS IN THE PARTICLE WORLD - NOBEL 2015

“The Nobel Prize in Physics 2015 recognises Takaaki Kajita in Japan and Arthur B. McDonald in Canada, for their key

contributions to the experiments which demonstrated that neutrinos change identities (flavours). This metamorphosis requires that neutrinos have mass. The discovery has changed our understanding of the innermost workings of matter and can prove crucial to our view of the universe.”

http://www.nobelprize.org

Takaaki Kajita Arthur B. McDonald

SOURCES OF NEUTRINOS

Trillions of neutrinos passing through our bodies every second — almost all of these are produced in fusion reactions in the Sun's core.

Atmospheric neutrinos Solar neutrinos

Other sources:

Big Bang cosmic rays Supernovas

…

WHAT IS A NEUTRINO? - THE POLTERGEIST “PARTICLE”

beta decay:

1930: W. Pauli’s letter:


“Dear Radioactive Ladies and Gentlemen …


there could exist electrically neutral particles, which I will call “neutrons”, that have spin 1/2 and obey the exclusion principle and that further differ from light quanta in that they do not travel with the velocity of light. The mass of the “neutrons” should be of the same order of magnitude as the electron mass and in any event not larger than 0.01 proton mass. ”

energy conservation:

1929, Niels Bohr: …”possible limitation of the conservation theorems …”

8

WHAT IS A NEUTRINO? - THE REAL PARTICLE

1931: The name neutrino by E. Fermi “the Italain little neutral one”

1934: The theory of beta decay by E. Fermi - (anti)neutrinos are included, produced!

1956: “Poltergeist is OVER” F. Reines & C. Cowan detect the trace of (anti)neutrino scintillation detector

Reines & Cowan 1958: neutrinos are ALWAYS left-handed

1934, Niels Bohr: “… I don’t yet feel fully convinced of the physical existence of the neutrino.”

THE HANDEDNESS - THE VAMPIRE NEUTRINO PARTICLE

momentum vs. spinning = handedness

neutrino

~p ⌫ _{~ p}

S ~ ~

S S ~

mirror

1957, Abdus Salam: “On reflecting a neutrino in a mirror, one sees nothing.”

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A

left-handed

v _A

⌫

THE MASS - NO AGE OF THE NEUTRINO

special relativity: massive particle can NEVER travel at the speed of light

MASSLESS NEUTRINO

Using massless particles in Dirac’s

equations violates left-right symmetry and results in two ‘components’

equation - neutrino (left) &

antineutrino (right).

two-handed

B

right-handed

¯

⌫

THE FLAVOURS- THE DIFFERENT NEUTRINOS

1937: the muon or “heavy electron” from cosmic ray 1949: pion, Yukawa’s particle

Bruno Pontecorvo in Dubna - investigate the muon decay:

µ ! e + µ ! e + 2⌫

conserve the ‘muon-ness’

n ! p + e + ¯⌫

conserve the ‘electron-ness’

TWO TYPES OF NEUTRINO

⌫

, ⌫

1975: a new lepton was found: the tau

conserve ‘tau-ness’

THREE FLAVOURS OF NEUTRINO

⌫

, ⌫

, ⌫

12

WHAT IS A NEUTRINO? - IN THE STANDARD MODEL

standard model

|ei

electron-flavour

|µi

muon-flavour

|⌧i

tau-flavour

MASSLESS & LEFT-HANDED “VAMPIRE”

NEUTRINO

particle

|f

i

|f

i

spontaneously

|f

i, |f

i

MASS EIGENSTATES - SHORT QUANTUM MECHANICS

14

special relativity, energy & momentum conservation:

E, p ! m

E

= p

c

+ m

c

It is ‘nonsense’ to speak about the mass if the

particle is characterised by fi quantum numbers

!

particle particle stays in this mass eigenstate

NO OSCILLATION between different states.

|mi

|mie

BECAUSE ONLY PARTICLE WITH MASS CAN OSCILLATE

Flavour oscillation can happen only if the mass eigenvalues are different!


The zero eigenvalue is excluded by the fact that all neutrinos are oscillating.

NEUTRINOS HAVE MASS

/1957, B. Pontecorovo suggests neutrino oscillation/

neutrino

spontaneously

⌫

|ei

|µi

ARE NOT MASS EIGENSTATES!

|ei, |µi

/coherent superposition/

|µi = P

j

µ

j

|m

ie

|ei = P

j e

j

|m

ie

W

e

⌫

=

SOLAR (E-)NEUTRINO PROBLEM (1968) - HOMESTAKE EXP.

16 SK: Super Kamiokande

SNO: Sudbury Neutrino Observatory

SNU: Solar Neutrino Unit

1 SNU = 1 reaction per 10³⁶ target per second)

experimental rate:

2.56 ± 0.32 SNU

theoretical rate:

8.5 ± 0.9 SNU

Standard Solar Model

deficit of solar neutrinos

NEUTRINO OSCILLATION?

p + p ! ²H + e⁺ + ⌫_e ⁸

B !

Be

+ e

+ ⌫

EXPENSIVE “DEEP & DARK SCIENCE” IN JAPAN & CANADA

SUPER KAMIOKANDE:

SUDBURY NEUTRINO OBSERVATORY:

- operational in 1999

- 1,000 tonnes heavy-water and for extra shielding ultra-pure water - all flavours of neutrinos (including ⁸B solar neutrinos)

- 9500 light detectors

- operational in 1996 (started 1991) - zinc mine

- 1000 m below Earth surface

- 50,000 tonnes of pure water (light beam can travel 70 m before intensity is 1/2) - more than 13,000 light detectors to detect Cherenkov radiation

- ⁸B solar neutrinos

- muon neutrinos (atmospheric)

SUPER KAMIOKANDE (SK) KAMIOKA, JAPAN

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SUDBURY NEUTRINO OBSERVATORY (SNO) CANADA, ONTARIO

photo: Lawrence Berkeley Nat'l Lab

ICECUBE - ANTARCTICA

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ICECUBE - THE LABORATORY

ATMOSPHERIC NEUTRINOS IN SK - YEAR 1998

The nobel prize in physics 2015, Popular science background 22 long(⌫_µ)

short(⌫_µ)

⇡ 50%

⌫

+ e ! ⌫

+ e

ISOTROPIC FLUX

NEUTRINOS IN SNO - YEAR 2001

reaction-2 reaction-1

1

(⌫

, Sun)

2

(all, Sun)

2(all, Sun) = _theory(⌫_e, Sun)

reaction-1:

reaction-2:

⌫_x + e ! ⌫^x + e

⌫

+

H ! e + p + p

⌫

+

H ! ⌫

+ p + n

NEUTRINO MASS - CONTRADICTIONS! STANDARD MODEL?

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Contradiction between left-handedness and mass!

1) right-handed neutrinos are not detected 2) extremely weak weak-interaction

Dirac neutrino

⌫ 6= ¯⌫

Majorana neutrino

⌫ = ¯ ⌫

theorists experimentalists

matter=antimatter superstring theory (11 dimensions)

Solution?

supersymmetry (SUSY), string theory, etc…

mass by Higgs mechanism mass by Higgs mechanism

FUNDAMENTAL “PHILOSOPHY”

WE NEED THE TECHNOLOGY TO MAKE IT

26

THANK YOU

CMS DETECTOR

MUON AND TAU NEUTRINOS (SNO WITH SK)

28

reaction-1

reaction-2

3.26

THE “AMAZING” NEUTRINOS - PROPERTIES

- In our Universe what we see are stars, galaxies, … but what we do not see that the

Universe is filled with neutrinos, the second most abundant particles in the Universe after photons; every cm³ of space contains around 300 neutrinos.

- Trillions of neutrinos are passing through our bodies every second — almost all of these are produced in fusion reactions in the Sun's core - interact only with the weak force.

H₂O

⇡ 1.7 ⇥ 10

m ⇡ 10

⇥ d(Sun-Earth)

- Direct mass measurements: “massless”?

5 ⇥ 10

m

⇡ m

⇡ m

1840

- Indirect mass measurements:

m

> 0

Pb

⇡ 1.5 ⇥ 10

m