complementarity of terrestrial neutrino experiments in searching for 13

Complementarity of Terrestrial Neutrino Experiments in

Searching for 13

Pasquale MigliozziINFN - Napoli

P.M., F. Terranova Phys. Lett. B 563 (2003) 73M. Komatsu, P.M., F. Terranova J. Phys. G. 29 (2003) 443

Pasquale Migliozzi - INFN Napoli

Outline

Definition of “on-peak” and “off-peak” experiment Two families scheme Three families scheme

Possible scenarios after first results of the planned experiments and implications 13 is so small the all give null result 13 is larger than 7° 4° < 13 < 7°

Conclusion


Two families scheme

Maximum oscillation rate at m2L/4E=/2 on peak

E

LmP

e 4sin2sin

222

In principle very easy, in practice very difficult!


m2 versus YEAR

Very difficult the tuning at the atmospheric mass scale!

Impact both on and e oscillation searches

NBPosc goes like (m2)2

From ’94 to ’03 it decreased by a factor 100!!

YEAR

1990

1994

1997

1998

1999

2001

2000

2003

m2 (

10

-3eV

2)Frejus

KamiokandeIMBSuper-KMacro

90% allowed regions for different exps as a function

of the time

Atmospheric exps


Comparing different scenariosin a two families scheme

Lim

it s a

t 90 %

C.L

. on

s in2 2

13 a

nd

13

(m

2 23=

2.5x

10-3 e

V2 ;

sin

2 23

=1)

Experiment sin2213 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

LI = n

om

inal C

NG

S; H

I = n

om

inal C

NG

S x

1.5

NB The CNGS sensitivity is limited by statistics very important high intensity proton beam

Phase I exps


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


The oscillation probability in the full PMNS scenario

A

A

A

A

A

A

A

A

A

A

A

A

2ˆ

ˆsin2sincos

ˆ1

ˆ1sinˆ

ˆsincoscossin

ˆ1

ˆ1sinˆ

ˆsinsinsinsin

ˆ1

ˆ1sinsin2sin

2

122

2322

13

13

2

2

232

132

CP

CP

eP

213

221

m

m

)1(2sin2sincos 231213

213

22ˆm

EnGA eF

E

Lm

4

213

O1 leading term

The hierarchy among thedifferent O terms depends onthe “on peak”-”off peak” choice

O2: 1 at osc. max

O3: 0 at osc. max

O4: suppressed by 2

O1

O2

O3

O4

Different dependence on sign(m223)

Possible sinergy between JHF and NuMI-OA

O1

O3

O2

O3Different hierarchy of O terms Possible synergies between “on” and “off” –axis exps.

All Phase I exps give null result

Can we start the construction of future facilities (Super-Beams, 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

To have an unambiguous answer the exps should 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 + anti-neutrino 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!


Three families analysis:sin2213 as a function of solar and atmospheric m2

m2sol/|m2

atmo|

/OPERA alone

OPERA alone5y HI beam

Limits on taken froma global fit to all availabledata: atmospheric+solar+reactor*

*M. Maltoni et al. hep-ph/03091303 allowed

This plot has been obtainedin the worst case: the larger value of 13 (varying CP) is taken


Accelerator expts. sensitivity vs CP

There are values forwhich the sensitivity on 13 is even better than the one compute in the 2-flavour approximation (CP=0).

Notice the different behaviour on m2 of theCNGS sensitivity Possible measurementof the sign of m2

31?


What happens if an exp decides to start with anti-neutrinos?

m2>0 m2<0

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!


13 issue

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

13 is larger than 7°

Signal already visible at MINOS/ICARUS/OPERA


CNGS at the start-up of JHF-SK

3 years data taking at the CNGS Sensitivity: sin2213 < 0.035 @ 90% C.L. (a factor 4 better than CHOOZ)

Indication (90% C.L) of e appearance if 13 > 7°

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)

90% C.L. allowed region

m2<0 m2>0


Allowed regions for JHF (5 years) + CNGS (8years)

13=5° 13=10°

m2<0 m2>0 m2<0 m2>0


Mass hierarchy with CNGS?

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(m2

23) (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) 3H. Minakata et al. Phys. Rev. D 68 (2003) 013010


Conclusion

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 m2

atm

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 m2

atm in neutrino mode

Final remark

For a successful future one should first exploit and optimise the

present

complementarity of terrestrial neutrino experiments in searching for 13

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