Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004 Aims of the meeting At least four...

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.


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 ~300 m12

2~7 10-5eV2 ~450 m23 2~ 2.5 10-3eV2 ~ 100 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 neutrinosAre neutrinos their own anti-particles?

=> an exciting experimental program for at least 25 years *)


Neutrinos Oscillations

After many years of research (since 1968) it is established since 1998that neutrinos change species when travelling through space. First observation: solar neutrinos! (150 000 000 km)second observation: neutrinos produced in the earth atmosphere goingthrough 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!


CHIPP ROADMAP Figure 2.1: The mass spectrum of the elementary particles. Neutrinos are 1012 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 statesin a split doublet with heavy neutrinos of mass scale interestinglysimilar to the grand unification scale.

mM <v>2 with <v> ~= mtop =174 GeV

meV

M ~1015GeV


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 1011-15 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!


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 experiment2. 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.


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.


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 withsmall funding from EU (FP6)ETHZ and UniGe have been also very active in the ECFA working groups


The aims of the meeting are therefore to review the situationand 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 meetingor a report to the CHIPP board be prepared.

Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004 Aims of the meeting At least four...

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