Cristina VOLPE(Institut de Physique Nucléaire Orsay, France)

Search for CP violationin the lepton sector

CP violation searches with future facilities

Conclusions

CP violation searches and astrophysics

OUTLINEOUTLINE

Introduction

Major advances in neutrino physics

e

SOURCEL

DETECTOR

e

AN IMPRESSIVE PROGRESS IN THE LAST DECADE in ourknowledge of its properties.

Pontecorvo, 1957

L/E ratio [km/GeV]

1 10 102 103 104

oscillationdecoherencedecay

1.61.41.2

10.80.60.40.2

data

/exp

ecta

tion

Many puzzles have been solved with an incredible impact on various domains of physics.

Among the fundamental implications…

The solar neutrino deficit problem is clarified.

We understand the energy production in stars.

Neutrinos are massive particles, contrary to whatwas believed for decades.

The origin of neutrino mass and its smallnessneeds to be understood.

It opens a new possibility to understand the matter versus anti-matter asymmetry in the Universe.

A key step for one of the major open questions in modern cosmology.

THE CP violating phase INTRODUCES A - ASYMMETRY.

3

e

1 12

23

13

3

2

1

1212

1212

1313

1313

2323

2323

100

0

0

0

010

0

0

0

001

cs

sc

ces

esc

cs

sci

ie 1

3

e

The two basis are related by a unitary matrix, called the Maki-Nakagawa-Sakata-Pontecorvo (MNSP) matrix.

ijijc cos ijijs sin

23 1312

THE 3-flavours OSCILLATION PARAMETERS In the case of three families, there are three mass eigenstates (1,2,3) and three flavour eigenstates (e,,).

23

21

22

23

21

22

3,1

2 mmmmmmmi

i Only two m2 are independent.

m212 m32

2

THE key OPEN QUESTIONS

> The mass hierarchy

> The third mixing angle 13

> The neutrino nature

> The Dirac phase

> The absolute mass scale

> The Majorana phases

Double-CHOOZ, Daya-Bay, T2K,..

KATRIN, MARE,…

Gerda, Cuore, Super-Nemo,…

from double-beta decay experiments

supernovae, -factories, double-beta,…

exciting discoveries might be close…

A wealth of experiments are under construction or at a R&D level.

13 – expected sensitivities

Discovery potential (90% CL) for sin2 213

from reactors and accelerators

P. Huber, M. Lindner, T. Schwetz, W. Winter, arXiv: 0907.1861

THE VALUE OF 13 CRUCIAL FOR FUTURE STRATEGIES.

CPV sensitivity

sensitivity limits (90% CL) from T2K, NOA and reactors

P. Huber, M. Lindner, T. Schwetz, W. Winter, arXiv: 0907.1861

LONG-TERM expensive PROJECTS might be necessary.

Long-term accelerator projects

> Super-beams - intense conventional beams from muon and pion decay > Beta-beams – intense and pure neutrino beams from boosted accelerated ions

> Neutrino factories – intense neutrino beams from stored muons

THE GOAL : to investigate very small 13 values, the Dirac CP phase and the mass hierarchy.

The beta -beam concept

ions at rest

ions are boosted

6He

6He

neutrino beams

Average neutrino energy : E = 2QFlux emittance : 1/.

No beam associated background (the -beams are produced from primary particles).

Zucchelli, PLB 2002

e6Li 6Li e

Beta-beams = 100

Low-energy = 5 -14

C. Volpe, Journ. Phys. G. 30 (2004), hep-ph/0303222.

Several beta-beam scenarios proposed

P. Zucchelli, Phys. Lett. B 2002

High-energy = 300

J. Burguet-Castell, D. Casper, JJ Gomez-Cadenas, P. Hernandez, F. Sanchez, Nucl. Phys. B695, 217 (2004), hep-ph/0312068.

and very high-energy = 1000

J. Bernabeu, J. Burguet-Castell, C. Espinoza, M. Lindroos, JHEP 0512 (2005) 014, hep-ph/0505054.

Electron-capture

See Volpe, Topical Review on “Beta-beams”, J.Phys.G34, R1 (2007) hep-ph/0605033

CP

THE standard baseline scenario

sourc

e

decayring

6He ,18Ne

PS

SPS

Proton driverSPL

ISOL productionISOL target &ion sourcebeam preparationECR pulsed

Ion accelerationLinac, 0.4 GeV

acceleration atmedium energyRCS, 1.5 GeV Acceleration to final energy

PS and SPS

e

To a far detector

IT REQUIRES THE PRODUCTION AND ACCELERATIONOF VERY INTENSE RADIOACTIVE IONS BEAMS (RIB).

8.7 GeV

93 GeVLss = 2.5 km

EURISOL

EURISOL Design Study (FP6 2005-2009) -> Conceptual Report

P. Zucchelli, Phys. Lett. B (2002)B. Autin et al. , J. Phys. G 29 (2003) 1785.

130 km

CERN

FREJUS

e

Frejus Underground Laboratory

60 m

MEGATONDETECTOR

65 m

MULTIPURPOSE DETECTORCP violation, (relic) supernova neutrinos and proton decay.

MULTIPURPOSE DETECTORCP violation, (relic) supernova neutrinos and proton decay.

THE SEARCH for CP and T violation:

CP T

(with Beta-beams) (conventional beams)

e (+) e (+)

e (-) e (-)Three technologies under study(water Cherenkov, scintillator,liquid argon) LAGUNA Design Study (2008-10)

Three technologies under study(water Cherenkov, scintillator,liquid argon) LAGUNA Design Study (2008-10)

THE standard baseline scenario

Two kinds of studies of the physics reach can be found :

1) based on values of the ion intensities and boosts that are obtained extrapolating well-known technologies and existing accelerators.

2)based on values of the ion intensities and boosts that are treated as “free” parameters, with the aim of exploring the conditions to achieve optimal sensitivities.

IN THE LITERATURE…

Sensitivity to 13 and CP violation

Mezzetto 2005

Campagne, Maltoni, Mezzetto, Schwetz, JHEP 0704:003 (2007). hep-ph/0603172

After 10 years running (5+5, or 2+8) with 440 kton detector,

5.8 (2.2) 10 18 6He (18Ne)/s, = 100

Synergy with athmospherics

Helps identify the mass hierarchy and the octant degeneracy.

Campagne, Maltoni, Mezzetto, Schwetz, JHEP 0704:003 (2007). hep-ph/0603172

First proposed in : . Hubert, Maltoni, Schwetz, Phys. Rev. D 71, 053006 (2005). hep-ph/0501037.

THE BETA-BEAM PROJECT IS A COMPETITIVE option.

Comparison with other facilities

ISSstudy

-beam

1

1

0.6

0.2

10-5 10-4 10-3 sin2213

Fract

ion

of

International Scoping Study Physics Working Group, arXiv: 0710.4947 .

close detector

PS

SPS

EURISOL

storage ring

BASELINE-nucleus cross sections(detector’s response,r-process, 2decay)

fundamental interactions studies (Weinberg angle, CVC test, )

PHYSICS POTENTIAL

astrophysical applications

PHYSICS STUDIED WITHIN THE EURISOL DS (FP6, 2005-2009)

EURISOL DS (2005-09): Some conclusionsTwo sets of candidate ions are being considered :6He/18Ne and 8B/8Li

The ion stacking method in the storage ring ok.

IMPORTANT PROGRESS ON THE FEASIBILITY PERFORMED.

Three ion production techniques have been and will be investigated.-the standard ISOL technique : the requires 6He intensity is achievable, the 18Ne intensity lower - direct production (M.Loislet-Leuven, M. Hass-Soreq, GANIL) : 6He and 18Ne intensities should be achievable- storage ring production : suitable for 8B/8Li.

The direct and storage ring production methods will be studied within EUROnu. C. Rubbia et al, NIM A 568(2006) 475.

Further work will be done within EUROnu both on the feasibility and on the physics reach.

If the ions are bunched to suppress the backgrounds, theremight be a conflict with the EURISOL requirements.

CP violation searches and astrophysics

Supernova neutrinos

E. Akhmedov, C.Lunardini & A.Smirnov, Nucl.Phys.B643 (2002) 339.

J Kneller and G.C. McLaughlin, arXiv:0904.3823.

A. B. Balantekin, J. Gava, C. Volpe, PLB662, 396 (2008), arXiv:0710.3112.

J. Gava, C. Volpe, Phys. Rev. D78, 083007(2008), arXiv:0807.3418.

Solar neutrinosH.Minakata and S. Watanabe, Phys. Lett. B 468, 256 (1999).

Walter Winter, Phys. Rev. D 74, 033015 (2006).

UHE neutrinos

NS

e

Core-collapse supernovae (SN)

99 % of the energy is emitted as neutrinos of all flavours in a short burst of about 10 s.

A possible site for thenucleosynthesis of the heavy elements, but present calculations fail to reproduce the observed abundances.

-PROPERTIES CAN HAVE EFFECTS IN THE STAR OR IMPACT THE SIGNAL IN A SN OBSERVATORY.

Neutrino propagation in media

There are also shock wave effects. These engender multiple resonances and phase effects.

Neutrino-neutrino interaction is important. A more complex problem : the neutrino evolution equations are non-linear.

IMPRESSIVE PROGRESS IN THE LAST FEW YEARS !

V() GF e.

e

e e

e

W

The Mikheev-Smirnov-Wolfenstein (MSW) effect (’78, ’86) : neutrino coupling with matter induces a resonant flavour conversion.

the beautiful explanation of the « solar neutrino deficit » problem !

E=20 MeV

t=1st=1.5s

Turbulence effects arejust being considered.

A lot of work still needs to be done …

A NEW UNDERSTANDING OF PROPAGATION IN SN :

See the review from Duan and Kneller, arXiv:0904.0974

Gava, Kneller, Volpe, McLaughlin, Phys. Rev. Lett. 103 (2009), arXiv:0902.0317

A SIGNATURE IN THE POSITRON TIME SIGNAL IF sin2213 > 10-5 OR sin213 < 10-5

The search for the third -mixing angle

FLUXES ON EARTHadiabatic

non-adiabatic

First calculation including the interaction and shock wave effects.

e + p n + e+

POSITRON TIME SIGNAL

The dip (bump) can be seen at 3.5 (1) sigma in Super-Kamiokande if a supernova at 10 kpc explodes..

29 MeV

15 MeV

The neutrino evolution equations in matter are

with

factorizes out easily and gives:

vacuum term

CP violation and core-collapse SNA. B. Balantekin, J. Gava, C. Volpe, PLB662, 396 (2008), arXiv:0710.3112

We have demonstrated under which conditions there can be CP violating effects in supernovae. Here the main steps :

matterterm

the T23 basis

The electron neutrino survival probability does not depend on .

This leads to the two following relations:

Evolution operator in the T23 basis

CP violation and core-collapse SN

J. Gava, C. Volpe, Phys. Rev. D78, 083007(2008), arXiv:0807.3418.

We have demonstrated that these relations also hold when the interaction is included.

Tree level

The electron neutrino flux in the SN:

AT TREE LEVEL THE e-FLUXES DO NOT DEPEND ON THE CP PHASE.

NS

The neutrinosphere is where neutrinos finally decouple from matter.

20 Km

L- neutrino fluxesat the neutrinosphere(Fermi-Dirac or power law )

THERE CAN BE CP-VIOLATION EFFECTS IN SUPERNOVAE.

In the Standard Model loop corrections for the v interaction with matter should be included.

Conditions for CP effects in SNBeyond the Standard Model mightintroduce differences in the and interaction wiht matter (Flavor Changing Neutral Currents, …).

at the neutrinosphere

The propagation Hamiltonian does not factorize any more !

AND also

More realistic case !

EFFECTS OF 5-10 % ON THE ELECTRON NEUTRINO FLUXES

in the SUPERNOVA.

- interaction and 1-loop

Standard MSW, tree level

Inverted hierarchy and small

Numerical results : effects on the flux ratios

J. Gava, C. Volpe, Phys. Rev. D78, 083007(2008), arXiv:0807.3418.

200 Km in the star

e (

= 1

80°)

/ e

( =

0°)

The electron fraction is a key parameter for the r-process nucleosynthesis :

VERY SMALL EFFECTS ON THE ELECTRON FRACTION.

Numerical results : effects on Ye

Ye (

= 1

80°)

/Ye (

= 0

°)

A. B. Balantekin, J. Gava, C. Volpe, PLB662, 396 (2008), arXiv:0710.3112

Conclusions

The value of 13 sets the strategy for CP violation searches.

Beta-beams - A very competitive option.-The report on the feasibility from the EURISOL DS soon available. Future studies (ex. ion intensity within EUROnu).

Neutrinos in core-collapse supernovae : We have set the basis for the exploration ofCP violation in dense media.

Andromeda (M31)

Danke.

Thank you!

Merci.

Grazie.