Neutrino Masses, Leptogenesis and Beyond The Incredible Foresight of ETTORE MAJORANA Haim Harari Erice, August 31, 2006

A 1  A 2 + e - e-e-  -Decay

N 1  N 2 + e - e-e- e-e- e-e- e-e-  -Decay

N 1  N 2 + e - e-e- e-e- e-e- e-e- Missing Energy Missing Momentum  -Decay

N 1  N 2 + e - + e-e- e-e- e-e- e-e- “Dear Radioactive Ladies & Gentlemen”  -Decay

n  p + e - + n p n p e-e- e-e- e-e- e-e- e-e-  -Decay

d  u + e - + n p n p e-e- e-e- e-e- e-e- e-e- e-e- d

The Elusive Neutrino No Electric Charge No Strong Interactions Spin = ½ Only Weak Interactions Small or Zero Mass If reach earth - one will hit something somewhere. With one thousand tons of water, and 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 stars Creation of heavy elements Energy of the sun Energy of stars Exploding 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 He 4 + 2e Energy Other Processes

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 Theory No 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” M 1 ~ O(  ) M 2 ~ O(m 2 /  0m m  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 GIMD ~2000GeV Perl ~1800MeV SLAC-LBL D  m(  ) = 1782 MeV

One or Two Neutrinos     e The schizophrenic  p p p P  Detector Brookhaven 1962  Is the “partner” of  the same as the “usual”, which comes with e ?  +  + +

 eV meVeVMeVkeVGeVTeV udud e () () 0 e 2/3 -1/3 d u 1 st Generation Q e ? Leptons Quarks

 eV meVeVMeVkeVGeVTeV udud e () () 0 e 2/3 -1/3 d u 1 st Generation Q  s c 2 nd cscs  () () 1970 GIM: “CHARM” e ?  ? Leptons Quarks

 eV meVeVMeVkeVGeVTeV udud e () () e ? 0 e 2/3 -1/3 d u 1 st Generation Q  s c 2 nd cscs  () () “The Standard Model” tbtb  () ()  b t 3 rd Quarks Leptons  ?  ?

udud () cscs () tbtb () “Mass Eigenstates” “Weak Eigenstates” Mixing Angles (small) Cabibbo

Is Massless or Very Light ?  m “See-Saw” M 1 ~ O(  ) M 2 ~ O(m 2 /  0m m  Majorana Mass Gell-Mann, Ramond, Slansky, Yanagida

PeV TeV GeV MeV keV eV meV  eV neV Planck GUT S.M.  t b c  s u d e   e

P i  j = Sin 2 2  ij Sin 2 (1.27  m 2 ij ) Km GeV LELE · eV 2 - Oscillations An Identity Crisis Reactor e Accelerator  Sun e    e   Mass Eigenstates Generation Eigenstates APPEARANCE DISAPPEARANCE

Three Mixing Angles e  12   23 e  13 - Oscillations P i  j = Sin 2 2  ij Sin 2 (1.27  m 2 ij ) Km GeV LELE · eV 2 LELE  m 2 << 1 P ~ 0  m 2 >> 1 P= ½ Sin 2 2  ij LELE  m 2 ~ O(1) probe  m LELE

Reactors: Accelerators: EL Probe  m 2 MeV GeV m km eV > ~ > ~ If m j >> m i  m 2 ij ~ m j 2 All experiments were : e   e e x  x - Oscillations Hence: limits only on  12 AllowedExcluded  m 2 eV Sin 2 2    

Cosmological Dark Matter The universe is 95% is Dark matter or Dark Energy What is the Dark Matter? Cosmic Background Radiation: 2.7°K per cm 3 : 400  110 e 110  110  If m( e ) + m(  ) + m(    ~ O(few e ) Closed Open flat Dark matter would be Hence: Crucial to search for    oscillations at O(eV)

“CHORUS” CERN No events  cannot account for most of the dark matter in the universe! Cosmological Dark Matter   Accelerator x  