Neutrino Masses, Leptogenesis and Beyond

Neutrino Masses, Leptogenesis and Beyond

The Incredible Foresight of ETTORE MAJORANA

Haim HarariErice, August 31, 2006

A1 A2 + e-

e-

-Decay

N1 N2 + e-

e-

e-

e-

e-

-Decay

N1 N2 + e-

e-

e-

e-

e-

Missing EnergyMissing Momentum

-Decay

N1 N2 + e- +

e-

e-

e-

e-

“Dear RadioactiveLadies & Gentlemen”

-Decay

n p + e- +

np

np

e-

e-

e-

e-

e-

-Decay

-Decay

d u + e- +

np

np

e-

e-

e-

e-

e-

e-

d

The Elusive Neutrino

No Electric ChargeNo Strong InteractionsSpin = ½Only Weak InteractionsSmall or Zero Mass

1016

If 1016 reach earth - one will hit something somewhere.

With one thousand tons of water, and 1016 every second since the big bang - 1 EVENT !!! Pauli: “I have done

a terrible thing!”

Creating Nuclei

n p + e- +

p n + e+ +

Creation of starsCreation of heavy elementsEnergy of the sunEnergy of starsExploding stars: supernova

The only way to convert a proton into a neutron

or vice versa – involves the neutrino!

n e- + p

p e+ + n

(Can you tell from ?)

The SUN

4p He4 + 2e+ + 2 + Energy

Other Processes

1957 - Neutrino Observed

Reines - Cowan

Big Problem: DETECTING Huge Problem: ELIMINATING BACKGROUND

Reactor n + p e+ + n

e+ + e- 2

n + Z Z’ +

The Foresight

Can you tell a neutrino from an

anti-neutrino?

MAJORANA

may be its own antiparticle !

Is Massless or Very Light ?

“Direct” experiments m (e) < few eV

TheoryNo good reason for massless Simple argument for very light . is the only “chargeless” particle.

All quarks and leptons “Dirac Mass” also “Majorana Mass”

Is Massless or Very Light ?

m

“See-Saw”

M1 ~ O()M2 ~ O(m2/

0 mm

Majorana Mass

Gell-Mann, Ramond, Slansky, Yanagida

Theorists predicted a new meson with a certain mass.

A particle was found soon after, having the right mass.

A second particle, very slightly heavier, was found soon after.

The second particle turned out to be the predicted meson.

The first particle turned out to be an unexplained heavy lepton,

identical to the electron in all its properties, except its mass.

Theorists predicted a new meson with a certain mass.

A particle was found soon after, having the right mass.

A second particle, very slightly heavier, was found soon after.

The second particle turned out to be the predicted meson.

The first particle turned out to be an unexplained heavy lepton,

identical to the electron in all its properties, except its mass.

Yukawa ~100MeV

Anderson-Neddermeyer ~100MeV

Powell

m (e) = 0.51 MeV m () = 106 MeV

Theorists predicted a new meson with a certain mass.

A particle was found soon after, having the right mass.

A second particle, very slightly heavier, was found soon after.

The second particle turned out to be the predicted meson.

The first particle turned out to be an unexplained heavy lepton,

identical to the electron in all its properties, except its mass.

m(e) = 0.51 MeV m() = 106 MeV

GIM D ~2000GeV

Perl ~1800MeV

SLAC-LBL

D

m() = 1782 MeV

One or Two Neutrinos

eThe schizophrenic

pp

p

P

Detector

Brookhaven 1962

Is the “partner” of the same as the “usual” ,which comes with e ?

+ + +

-6 -5 -4 -2-3 -1 -0 1 2 3 4 5 6 7 8 9 10 11 12eV meV eV MeVkeV GeV TeV

ud

ee

( )

( )

0

-1e

2/3

-1/3du

1stGeneration Q

e?Leptons

Quarks

-6 -5 -4 -2-3 -1 -0 1 2 3 4 5 6 7 8 9 10 11 12eV meV eV MeVkeV GeV TeV

ud

ee

( )

( )

0

-1e

2/3

-1/3du

1stGeneration Q

sc

2nd

cs

( )

( )1970 GIM: “CHARM”

e? ?Leptons

Quarks

-6 -5 -4 -2-3 -1 -0 1 2 3 4 5 6 7 8 9 10 11 12eV meV eV MeVkeV GeV TeV

ud

ee

( )

( )

e? 0

-1e

2/3

-1/3du

1stGeneration Q

sc

2nd

cs

( )

( )“The Standard Model”

tb

( )

( )

bt

3rd

Quarks

Leptons? ?

ud( ) c

s( ) tb( )

“Mass Eigenstates”“Weak Eigenstates”

MixingMixingAngles(small)

Cabibbo

Is Massless or Very Light ?

m

“See-Saw”

M1 ~ O()M2 ~ O(m2/

0 mm

Majorana Mass

Gell-Mann, Ramond, Slansky, Yanagida

-12

-9

-6

-3

03

6

9

12

15

18

21

24

27

30

PeVTeV

GeVMeVkeVeV

meVeVneV

PlanckGUT

S.M.

tbc su de

e

Pij = Sin 2 2ij Sin 2 (1.27 m2ij)

KmGeV

LE

· eV2

- Oscillations

An Identity CrisisReactor e

Accelerator

Sun e

e

Mass Eigenstates

GenerationEigenstates

APPEARANCEDISAPPEARANCE

Three Mixing Angles

e 12 23

e 13

- Oscillations

Pij = Sin 2 2ij Sin 2 (1.27 m2ij)

KmGeV

LE

· eV2

LE m2 << 1 P ~ 0

m2 >> 1 P= ½ Sin2 2ijLE

m2 ~ O(1) probe mLE

Reactors:

Accelerators:

E L Probe m2

MeV

GeV

m

km

eV>~eV>~

If mj >> mi m2ij ~ mj

2

All experiments were :e ee x x

- Oscillations

Hence: limits only on 12

Allowed Excluded

m2 eV2

1000

100

10

1

0.1

Sin2 2

Cosmological Dark Matter

The universe is

95% is Dark matter or Dark EnergyWhat is the Dark Matter? Cosmic Background

Radiation: 2.7°Kper cm3: 400

110 e

110

110

If m(e ) + m() + m(~ O(few e)

ClosedOpenflat

Dark matter would be Hence: Crucial to search for

oscillations at O(eV)

“CHORUS”CERN 1990 - 98

No events

cannot account for most of the dark matter in the universe!

Cosmological Dark Matter

Accelerator x