Cristina VOLPE (Institut de Physique Nucléaire Orsay, France) Search for CP violation in the lepton sector

CP violation searches with future facilities Conclusions CP violation searches and astrophysics OUTLINE Introduction

Major advances in neutrino physics e SOURCE L DETECTOR   e AN IMPRESSIVE PROGRESS IN THE LAST DECADE in our knowledge of its properties. Pontecorvo, 1957 L /E ratio [km/GeV] oscillation decoherence decay data/expectation 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 what was believed for decades. The origin of neutrino mass and its smallness needs 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 1  3 e   The two basis are related by a unitary matrix, called the Maki-Nakagawa-Sakata- Pontecorvo (MNSP) matrix.  23  13  12 THE 3-flavours OSCILLATION PARAMETERS In the case of three families, there are three mass eigenstates ( 1, 2, 3 ) and three flavour eigenstates ( e, ,  ). Only two  m 2 are independent.  m 21 2  m 32 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 sin 2 2  13 from reactors and accelerators P. Huber, M. Lindner, T. Schwetz, W. Winter, arXiv: THE VALUE OF  13 CRUCIAL FOR FUTURE STRATEGIES.

CPV sensitivity sensitivity limits (90% CL) from T2K, NO A and reactors P. Huber, M. Lindner, T. Schwetz, W. Winter, arXiv: 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 6 He neutrino beams Average neutrino energy : E = 2  Q   Flux emittance : 1/ . No beam associated background (the -beams are produced from primary particles). Zucchelli, PLB 2002 e 6 Li e

Beta-beams  = 100 Low-energy  = C. Volpe, Journ. Phys. G. 30 (2004), hep-ph/ 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/ and very high-energy  = 1000 J. Bernabeu, J. Burguet-Castell, C. Espinoza, M. Lindroos, JHEP 0512 (2005) 014, hep-ph/ Electron-capture See Volpe, Topical Review on “Beta-beams”, J.Phys.G34, R1 (2007) hep-ph/ CP

THE standard baseline scenario source decay ring 6 He, 18 Ne PS SPS Proton driver SPL ISOL production ISOL target & ion source beam preparation ECR pulsed Ion acceleration Linac, 0.4 GeV acceleration at medium energy RCS, 1.5 GeV Acceleration to final energy PS and SPS e To a far detector IT REQUIRES THE PRODUCTION AND ACCELERATION OF VERY INTENSE RADIOACTIVE IONS BEAMS (RIB). 8.7 GeV 93 GeV Lss = 2.5 km EURISOL EURISOL Design Study (FP ) -> 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 MEGATON DETECTOR 65 m MULTIPURPOSE DETECTOR CP violation, (relic) supernova neutrinos and proton decay. MULTIPURPOSE DETECTOR CP 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 ( ) Three technologies under study (water Cherenkov, scintillator, liquid argon) LAGUNA Design Study ( ) 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/ After 10 years running (5+5, or 2+8) with 440 kton detector, 5.8 (2.2) He ( 18 Ne)/s,  = 100

Synergy with athmospherics Helps identify the mass hierarchy and the octant degeneracy. Campagne, Maltoni, Mezzetto, Schwetz, JHEP 0704:003 (2007). hep-ph/ First proposed in :. Hubert, Maltoni, Schwetz, Phys. Rev. D 71, (2005). hep-ph/

THE BETA-BEAM PROJECT IS A COMPETITIVE option. Comparison with other facilities ISS study  - beam sin 2 2  13 Fraction of  International Scoping Study Physics Working Group, arXiv:

C.Volpe, J Phys G 30 (2004). LOW ENERGY BETA-BEAMS A proposal to establish a facility for the production of intense and pure low energy neutrino beams (100 MeV). close detector PS SPS EURISOLEURISOL storage ring BASELINE -nucleus cross sections (detector’s response, r-process, 2  decay) fundamental interactions studies (Weinberg angle, CVC test,  ) PHYSICS POTENTIAL astrophysical applications PHYSICS STUDIED WITHIN THE EURISOL DS (FP6, )

EURISOL DS ( ): Some conclusions Two sets of candidate ions are being considered : 6 He/ 18 Ne and 8 B/ 8 Li 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 6 He intensity is achievable, the 18 Ne intensity lower - direct production (M.Loislet-Leuven, M. Hass-Soreq, GANIL) : 6 He and 18 Ne intensities should be achievable - storage ring production : suitable for 8 B/ 8 Li. 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, there might 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: A. B. Balantekin, J. Gava, C. Volpe, PLB662, 396 (2008), arXiv: J. Gava, C. Volpe, Phys. Rev. D78, (2008), arXiv: Solar neutrinos H.Minakata and S. Watanabe, Phys. Lett. B 468, 256 (1999). Walter Winter, Phys. Rev. D 74, (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 the nucleosynthesis 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 (  ) G F  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=1s t=1.5s Turbulence effects are just 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:

Gava, Kneller, Volpe, McLaughlin, Phys. Rev. Lett. 103 (2009), arXiv: A SIGNATURE IN THE POSITRON TIME SIGNAL IF sin 2 2  13 > OR sin2  13 < The search for the third -mixing angle FLUXES ON EARTH adiabatic 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 SN A. B. Balantekin, J. Gava, C. Volpe, PLB662, 396 (2008), arXiv: 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 T 23 basis CP violation and core-collapse SN J. Gava, C. Volpe, Phys. Rev. D78, (2008), arXiv: 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 fluxes at 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 SN Beyond the Standard Model might  introduce 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, (2008), arXiv: Km in the star  e (  = 180 °)/  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

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 of CP violation in dense media.

Andromeda (M31) Danke. Thank you! Merci. Grazie.