Faster-than-light neutrinos?

Just about two hours ago in CERN, there was a groundbreaking claim about an experiment detecting neutrinos that travel faster than light.  The OPERA experiment in Gran Sasso, Italy collected data and analysed the speed of these tiny particles that only interact gravitationally and weakly since neutrinos are neutral leptons.  They have shown in their experiment that the speed of the neutrinos were faster than light by a factor of

(2.48 ± 0.28 (statistical errors) ± 0.30 (systematic errors) ) ×10^-5

or 6.0 σ.  It is big news all over the world with major news networks(for example, BBC) reporting them on webpages and TV channels.

The auditorium room filling up half and hour before the seminar starts.
I am really lucky to get a seat at the back  row!

The speaker, Dario Autiero (Institut de Physique Nucleaire de Lyon)

So what are neutrinos?  Originally, they are postulated to exist by Wolfgang Pauli to explain missing transverse energy of beta decay.  A simple representative decay process would be neutron decay.

But then when they measured the energy of the beta particle, or the fast electron, they found that the reaction did not obey the Law of Conservation of Energy.  So W. Pauli thought that maybe there is some kind of small undetected particle that carried that energy away.  Now we know to reasonable doubt that this is true so we rewrite this decay process as

Now that we got rid of the basic question of what neutrinos really are, you may ask, what was OPERA's experiment about?  Well, OPERA was trying to catch neutrinos that change flavours.  Flavours?  We now know that there are three flavours.  The electron neutrino, muon neutrino and the tau neutrino and by changing flavours (or the technical term is neutrino oscillation) the electron neutrino changes in the muon or tau neutrino.  The OPERA experiment is an appearance experiment; to detect the appearance of tau neutrinos from the oscillation of muon neutrinos sent from CERN.

They are still looking for tau neutrinos right now.  At the same time, they need some kind of accurate measurements of distance and time since the travel time from CERN to Gran Sasso, Italy (730km) took the muon neutrinos only 3ms.  They used GPS synchronizations for timing and help from land surveying to figure out the distance accurate to the centimeter level.  According to them, after months of checking and rechecking their results they decided that their experimental results and analysis work were correct and decided to show it to the world.  In particle physics, it is enough to claim discovery with a 5.0 σ significance (signal over background events).

The CERN Neutrinos to Gran Sasso (CNGS) beam line.  It produces muon neutrinos from a proton beam source accelerated  by the proton synchrotron in CERN.  The protons hit a target producing pions and kaons that decay into muons and neutrinos.  The neutrinos then pass through 730km of earth and rock to reach the OPERA experiment in Italy.    They could do that because they very rarely interact with matter.