Transcript ppt

Complementarity of Terrestrial
Neutrino Experiments in
Searching for 13
Pasquale Migliozzi
INFN - Napoli
P.M., F. Terranova Phys. Lett. B 563 (2003) 73
M. Komatsu, P.M., F. Terranova J. Phys. G. 29 (2003) 443
Outline
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Definition of “on-peak” and “off-peak” experiment
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Possible scenarios after first results of the
planned experiments and implications
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Two families scheme
Three families scheme
13 is so small the all give null result
13 is larger than 7°
4° < 13 < 7°
Conclusion
Pasquale Migliozzi - INFN Napoli
Two families scheme
Dm L
 sin 2 sin
4E
2
P   e
2
2
Maximum oscillation rate at Dm2L/4E=p/2  on peak
In principle very easy, in practice very difficult!
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Dm2 versus YEAR
90% allowed regions
for different exps as
a function of the time
Frejus
Kamiokande
IMB
Super-K
Macro
Dm2 (10-3eV2)
Atmospheric exps
NB
YEAR
Posc goes like (Dm2)2
From ’94 to ’03 it
decreased by a
factor 100!!
Very difficult the tuning at the atmospheric mass scale!
Impact both on t and  e oscillation searches
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Experiment
sin2213
13
CHOOZ
<0.14
<11º
MINOS 2yr
<0.06
<7.1º
ICARUS 5yr
<0.04 (LI)
<0.03(HI)
<5.8º
<5.0º
OPERA 5yr
 CNGS
<0.06(LI)
<0.05(HI)
<7.1º
<6.4º
ICARUS+OPERA 5yr
<0.03(LI)
<0.025(HI)
<5.0º
<4.5º
JHF 5yr
<0.006
<2.5º
Phase I exps
NB The CNGS sensitivity is limited by statistics
 very important high intensity proton beam
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LI = nominal CNGS; HI = nominal CNGS x 1.5
Comparing different scenarios
in a two families scheme
Comment
Historically different projects have been compared by looking
at the sensitivity computed assuming the two families scheme.
However, this approximation is to simple: neutrino are at least
three and are connected among them.
 Interplay between 13 and the CP phase
 The sensitivity depends on solar parameters
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The oscillation probability in
the full PMNS scenario
sin 1  Aˆ D 
O1 leading term
 sin 2 sin 
1  Aˆ 
sin Aˆ D  sin 1  Aˆ D 
O : 1 at osc. max
  sin   sin  sin D
1  Aˆ 
Aˆ
sin Aˆ D  sin 1  Aˆ D 
  sin   cos  cos D
O : 0 at osc. max
ˆ
ˆ
1  A
A
sin Aˆ D 
  cos  sin 2
O : suppressed by 
2
P   e
2
2
13
23
2
13
CP
2
13
CP
3
2
2
2
2
23
12
4
Aˆ
2
2
Dm21

  cos13 sin 212 sin 2 23  (1)
2
Dm13
2
E
D
m
13 L
ˆ
A  2 2GF ne
D
2
Dm13
4E
The hierarchy among the
different O terms depends on
the “on peak”-”off peak” choice
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2
O1
O2
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O3

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O4
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
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Different dependence on sign(Dm223)
 Possible sinergy between JHF and NuMI-OA
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Different hierarchy of O terms
 Possible synergies between
“on” and “off” –axis exps.
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
 
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

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


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O1
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O3

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
O2


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

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O3
All Phase I exps give null result
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Can we start the construction of future facilities (SuperBeams, Neutrino Factories) on firm bases?
Can we safely exclude large values of 13 such that CP is not
visible at future facilities (i.e. stop future programs)?
The answer is no!
Some considerations
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To have an unambiguous answer the exps should
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Perform a pure measurement of 13 (e.g. reactors)
Be able to disentangle 13- intrinsic correlations which could
result into an apparent suppression of 13 (e.g. neutrino + antineutrino run)
Have maximal 13 sensitivity for maximal CP violation
The only thing we can do with the proposed
experiments is to OPTIMIZE THE DATA TAKING!
Pasquale Migliozzi - INFN Napoli
Three families analysis:
sin2213 as a function of solar and atmospheric Dm2
  Dm2sol/|Dm2atmo|
OPERA alone
5y HI beam
This plot has been obtained
in the worst case:
the larger value of 13
(varying CP) is taken
/OPERA alone
3s allowed
Limits on  taken from
a global fit to all available
data: atmospheric+solar+reactor*
*M. Maltoni et al. hep-ph/0309130
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Accelerator expts.
sensitivity vs CP
There are ip values for
which the sensitivity on 13
is even better than the one
compute in the 2-flavour
approximation (CP=0).
Notice the different
behaviour on Dm2 of the
CNGS sensitivity
 Possible measurement
of the sign of Dm231?
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What happens if an exp decides to
start with anti-neutrinos?
At the present NuMI-OA is supposed to start data-taking with 
BAD CHOICE: results similar to JHF, no synergies
GOOD CHOICE: would be data-taking with anti-, synergies!
Dm2>0
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Dm2<0
13 issue
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The measurement of 13 is made complicated by the fact
that oscillation probability is affected by matter effects
and possible CP violation
Because of this, there is not a unique mathematical
relationship between oscillation probability and 13
Especially for low values of 13, sensitivity of an experiment
to seeing e depends very much on 
Several experiments with different conditions and with
both  and anti- will be necessary to disentangle these
effects
Pasquale Migliozzi - INFN Napoli
13 is larger than 7°
Signal already visible at
MINOS/ICARUS/OPERA
CNGS at the start-up of JHF-SK
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3 years data taking at the CNGS
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Sensitivity: sin2213 < 0.035 @ 90% C.L. (a factor 4 better than CHOOZ)
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Indication (90% C.L) of e appearance if 13 > 7°
90% C.L. allowed region
13|true
13|min
13|max
1
---
5.5
---
2.5
---
5.8
---
5.0
---
7.0
---
7.5
1.2
11.4
(7.5+3.9-6.3)
10
5.6
13.7
(10.+3.7-4.4)
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Dm2<0
Dm2>0
Allowed regions for
JHF (5 years) + CNGS (8years)
13=5°
Dm2<0
Dm2>0
13=10°
Dm2<0
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Dm2>0
Mass hierarchy with CNGS?
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13 in the range 4° to 7°
Off-peak exps do not contribute to the 13 business
 Run JHF with  and NuMI-OA with anti- will be the
optimal solution to lift the -13 correlation
 Run both JHF and NuMI-OA with  in order to measure
the sign(Dm223) (e.g. the two exps have different matter effects)

V. Barger et al. Phys. Lett. B 560 (2003) 75
P. Huber et al. Nucl. Phys. B 654 (2003) 3
H. Minakata et al. Phys. Rev. D 68 (2003) 013010
Conclusion
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Null result at Phase I exps : WARNING! CP could be huge but hidden by
the choice of the neutrino run. A dangerous manifestation of the ( -13)
correlation!
The anti- choice (done after the  run or in parallel by NUMI-OA) is
mandatory to take decisions about the Phase II
Positive result at MINOS or CNGS: Great time for oscillation physics!
Synergic use of MINOS+ CNGS + JHF + NuMI-OA:
 to constrain (-13)
 to determine the sign of Dm2atm
4° < 13 < 7° Another great season for Japanese neutrino physics!
Signal seen at JPARC. NuMI-OA contribute to precision measurement
of (-13) in anti- mode, sign Dm2atm in neutrino mode
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Final remark
For a successful future one should
first exploit and optimise the present