1. Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004 Aims of the meeting At least four universities in Switzerland do research in Neutrino Physics. It is felt that the subject is very important (one of the three pillars of particle physics in the forseable future), but that we would benefit from sharing our views on this future. Even before the birth of CHIPP it had been envisaged to assemble the Swiss neutrino community to share our activities, discuss physics and define our longer time goals in common. The advent of CHIPP has given this project a natural framework.

2. Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004 1.We know that there are three families of active, light neutrinos (LEP) 2.Solar neutrino oscillations are established (Homestake+Gallium+Kam+SK+SNO+KamLAND) 3.Atmospheric (   ) oscillations are established (IMB+Kam+SK+Macro+Sudan+K2K) 4.At that frequency, electron neutrino oscillations are small (CHOOZ) This allows a consistent picture with 3-family oscillations    ~30 0  m 12 2 ~7 10 -5 eV 2    ~45 0  m 23 2 ~ 2.5 10 -3 eV 2    ~ 10 0 with several unknown parameters    mass hierarchy Where are we? *)to set the scale: CP violation in quarks was discovered in 1964 and there is still an important program (K0pi0, B-factories, Neutron EDM, LHCb, BTeV….) to go on for >>10 years…i.e. a total of >50 yrs. and we have not discovered leptonic CP yet! Where do we go? leptonic CP & T violations Determination of the absolute mass scale of neutrinos Are neutrinos their own anti-particles? => an exciting experimental program for at least 25 years *)

3. Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004 Neutrinos Oscillations After many years of research (since 1968) it is established since 1998 that neutrinos change species when travelling through space. First observation: solar neutrinos! (150 000 000 km) second observation: neutrinos produced in the earth atmosphere going through earth(13000 km) recently 2003 (exp. K2K ) neutrinos from man made beams par l'homme. Observation of a quantum phenomenon over distances of hundred to millions of kilomètres!

4. Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004 CHIPP ROADMAP Figure 2.1: The mass spectrum of the elementary particles. Neutrinos are 10 12 times lighter than other elementary fermions. The hierarchy of this spectrum remains a puzzle of particle physics. Most attractive wisdom: via the see-saw mwchanism, the neutrinos are very light because they are low-lying states in a split doublet with heavy neutrinos of mass scale interestingly similar to the grand unification scale. m   M  2 with ~= m top =174 GeV m     eV M ~10 15  GeV

5. Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004

6. LEPTONIC T, CP VIOLATION The baryon asymmetry in the Universe… requires CP or T violation. That of the quarks is not enough! Boris Kayser This leptonic asymmetry would in turn generate baryon asymmetry. (energies typical of the particles that would be exchanged in Baryon decay 10 11-15 GeV or so) NB this is CP asymmetry for the Heavy Majorana Neutrinos 1. we don’t know if neutrinos are Majorana particles 2. The CP phases that enter are those of the heavy neutrinos, not the light ones. Nevertheless: leptonic CP violation may be the reason why we exist… lets look for it!

7. Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004 In our preliminary discussions we identified four main topics of discussion for this time: 0. the present activities (HARP/K2K, OPERA, ICARUS) 1. the J-Parc programme and the T2K experiment 2. the neutrinoless double beta decay experiments 3. the possibilities for the longer term future in Europe. CF the CHIPP roadmap: Recommendation 4 – Neutrino Physics and the Near Future The CERN CNGS program is well advanced with the beam nearing completion and the OPERA and ICARUS experiments due to collect data from 2006 for at least 5 years. During that period, the experiments must be maintained and the data exploited, and we recommend the necessary funding for that. The neutrino program (J-PARC neutrino) proposed in Japan should allow significantly improved measurements in the neutrino sector from about 2008 for at least 5 years. An active and visible contribution by Swiss groups to should be investigated.

8. Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004 The neutrino programme occupies presently 17 scientists and 14 students (plus a few others who think about it…) Free valences will appear this year (Harp/K2K group) and around 2006/7 when the construction of OPERA & ICARUS is completed. It is however evident that the time scales for new possible involvements are different between Geneva an the goups involved in CNGS. It is also possible that groups from other activities switch to neutrinos.

9. Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004 On the longer time-scale, although the accelerator R&D at CERN is very limited, there is much discussion at CERN of a possible Multi - Megawatt machine (SPL or similar 'proton driver) which would allow -- high intensity conventional neutrino beams (superbeam) -- or novel neutrino beams (beta-beam, muon based neutrino factory) Geneva Bern Neuchatel and U.Zurich are members of BENE (Beams for European Neutrino Experiments) a European Network with small funding from EU (FP6) ETHZ and UniGe have been also very active in the ECFA working groups

10. Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004 The aims of the meeting are therefore to review the situation and our involvements in the above topics, and to allow ample time for physics discussions, emergence of possible synergies, and hopefully of a coherent programme of research. 1. The transparencies of the meeting will be posted on the web 2. we should discuss the opportunity that a summary of the meeting or a report to the CHIPP board be prepared.

11. Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004