RENCONTRES DU VIETNAM NEUTRINOS! « Social responsabilities, political correctness » Women/Men = 13/38 London = 11/56 Asia/Rest of world =16/35 10/57

What are they good for? Neutrinos, they are very small They have no charge and have no mass And do not interact at all. The earth is just a silly ball To them, through which they simply pass, Like dustmaids down a drafty hall Or photons through a sheet of glass. They snub the most exquisite gas, Ignore the most substantial wall, Cold-shoulder steel and sounding brass, Insult the stallion in his stall, And, scoring barriers of class, Infiltrate you and me. Like tall And painless guillotines, they fall Down through our heads into the grass. At night, they enter at Nepal And pierce the lover and his lass From underneath the bed-you call It wonderful: I call it crass. John Updike

nm nm ne nt nm nt ne ne nt ne nm nt nm

A double-faced particle

Sources of neutrinos

Portrait of a neutrino

Recent progresses Neutrinos have masses! … very tiny! The heaviest type of neutrino has a mass 20 billion times smaller than the that of the proton. The Big Bang model predicts 2 billion times more neutrinos than nucleons. Stunning conclusion : neutrinos weigh as much as all the stars of all the galaxies! But… there is much more in the Universe!!

The three fundamental questions Where is antimatter gone? Leptogenesis? What is the nature of Dark Matter? Heavy neutrinos? What is Dark Energy? Varying mass neutrinos?

Rigmarole of pending questions Why 3 active neutrinos? Hierarchy, normal or inverted ? Violation of CP ? Nature of the neutrinos, Dirac or Majorana? Electromagnetic interactions? Sterile/heavy neutrinos? Neutrinos in astrophysics? Cosmological neutrinos ?