Alain Blondel CHIPP Neutrino meeting NEUCHATEL 21-22 June 2004

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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.
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Where are we?

• We know that there are three families of active,
  light neutrinos (LEP)
• Solar neutrino oscillations are established
  (HomestakeGalliumKamSKSNOKamLAND)
• Atmospheric (nm -gt ) oscillations are established
  (IMBKamSKMacroSudanK2K)
• At that frequency, electron neutrino oscillations
  are small (CHOOZ)
• This allows a consistent picture with
  3-family oscillations
• q12 300 Dm1227 10-5eV2
  q23 450 Dm23 2 2.5 10-3eV2 q13
  lt 100
• with several unknown parameters q13, d,
  mass hierarchy

leptonic CP T violations
Where do we go?
Determination of the absolute mass scale of
neutrinos Are neutrinos their own anti-particles?

• gt an exciting experimental program for at least
  25 years )

)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 gtgt10 yearsi.e.
a total of gt50 yrs.
and
we have not discovered leptonic CP yet!
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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 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!
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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 states in a split doublet with
heavy neutrinos of mass scale interestingly simila
r to the grand unification scale. mn. M ltvgt2
with ltvgt mtop 174
GeV mn. O(10-2) eV
M 1015
GeV
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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 dont
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!
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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.
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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.
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On the longer time-scale, although the
accelerator RD 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
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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.
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