Neutrino oscillations: Perspectives (… for LENA?)

Neutrino oscillations: Perspectives (… for LENA?)

LENA strategy meetingDESY Hamburg, GermanyJune 14, 2012

Walter WinterUniversität Würzburg

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Contents

Questions of interest Consequences of large 13 discovery

Worldwide picture Comments on superbeam

CERN-Pyhäsalmi Sterile neutrinos (briefly) Summary

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Three flavor mixing

Use same parameterization as for CKM matrix

Pontecorvo-Maki-Nakagawa-Sakata matrix

( ) ( ) ( )= xx

(sij = sin ij cij = cos ij)

Potential CP violation ~ 13

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Why is CP interesting?

CP violationNecessary condition for successful baryogenesis (dynamical mechanism to create matter-antimatter asymmetry of the universe) thermal leptogensis by decay of heavy see-saw partner?

Model building

e.g. TBM sum rule: 12 = 35 + 13 cos(Antusch,

King)

Need performance which is equally good for all CP

Symmetrye.g. TBM, BM, …?

Correction leadingto non-zero 13?

sin

cos

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Mass spectrum/hierarchy

Specific models typically come together with specific MH prediction

Good model discriminator(Albright, Chen, hep-ph/0608137)

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Normal Inverted

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13 discovery 2012

First evidence from T2K, Double Chooz Discovery (~ 5) independently (?)

by Daya Bay, RENO

(from arXiv:1204.1249)

1 error bars

Daya Bay 3

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Three flavors: 6 params(3 angles, one phase; 2 x m2)

Describes solar and atmospheric neutrino anomalies, as well as reactor antineutrino disapp.!

Neutrino oscillations: Summary

Coupling: 13

Atmosphericoscillations:Amplitude: 23

Frequency: m312

Solaroscillations:Amplitude: 12

Frequency: m212

Suppressed

effect: CP

(Super-K, 1998;Chooz, 1999; SNO 2001+2002; KamLAND 2002;Daya Bay, RENO 2012)

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Consequences of large 13

13 well measured by Daya Bay

MH/CPV difficultNeed new facility!

Huber, Lindner, Schwetz, Winter, 2009

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Mass hierarchy measurement?

Mass hierarchy [sgn(m2)] discovery possible with atmospheric neutrinos? (liquid argon, HyperK, MEMPHYS, INO, PINGU?, LENA?, …)

Barger et al, arXiv:1203.6012;IH more challenging

NB: basically any long-baseline experiment at design luminosity with E > 1 GeV and L >> 1000 km can for all CP measure the hierarchy by sufficient Earth matter effects (MSW effect)!

Perhaps differentfacilities for MH and CPV

proposed/discussed?

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There are three possibilities to artificially produce neutrinos:

Beta decay:Example: Nuclear reactors, Beta beams

Pion decay:From accelerators:

Muon decay:Muons produced by pion decays! Neutrino Factory

Muons,neutrinos

Long-baseline neutrino sources

Protons

Target Selection,focusing

Pions

Decaytunnel

Absorber

Neutrinos

Superbeam

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The new paradigm: Precision?

CP violation performance represents only two possible values of CP (0 and )Need new performance

indicatorsReveal that

some experiments (narrow beam spectra!) strongly optimized for CPV (Coloma, Donini, Fernandez-Martinez,

Hernandez, 2012; concept: WW, PRD 70 (2004) 033006 )

Bands: 13 allowed ranges

C2P = LBNO:CERN-PyhäsalmiL~2300 km, 100kt

liquid argon

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The big unknown: Systematics

Systematics important for large 13

New treatment neededUse explicit near-far

detector simulationsUse same knowledge for

cross sections for all experiments

Use same assumptions for systematics implementation!

(Huber, Mezzetto, Schwetz, 2007)(Coloma, Huber, Kopp, Winter, in preparation)

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Systematics: Values?

(Coloma, Huber, Kopp, Winter, in preparation)

Educated guessof param. range

Same parameters for all superbeams:LBNE, LBNO, …

Same assumptions for X-sections

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New performance indicator

(Coloma, Huber, Kopp, Winter, in preparation)

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Precision:

Worldwide comparison

(Coloma, Huber, Kopp, Winter, in preparation)

CKM phase

(bands: systematics

opt.-cons.

includesmatter density

uncertainty 1% - 5%)

Most robust wrt systematics?

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Superbeam CERN-Pyhäsalmi

Main impact factors:Neutral current

backgrounds versus efficiency

Fiducial volume (cost?)

Background migration

(no migration matrices yet: NC backgrounds reconstructed in energy window of signal)

(special thanks: Pilar Coloma)

100 kt liquid argon

50 kt LENA

90% eff.10% NC

50 kt LENA

90% eff.30% NC

L ~ 2300 km

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Evidence for sterile neutrinos?

LSND/MiniBooNE Reactor+gallium anomalies

Global fits(M

iniB

ooN

E @

Neu

trin

o 20

12)

(B. F

lemin

g, TA

UP

2011)

(Kopp, Maltoni, Schwetz, 1103.4570)

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Example: 3+1 framework

Well known tension between appearance and disapp. data (appearance disapp. in both channels)

Need one or more new experiments which can test e disappearance (Gallium, reactor anomalies) disappearance (overconstrains 3+N frameworks) e- oscillations (LSND, MiniBooNE) Neutrinos and antineutrinos separately (CP violation? Gallium vs reactor?)

Example: nuSTORM - Neutrinos from STORed Muons (LOI: arXiv:1206.0294) LENA: see C. Hagner‘s talk!Summary of options: Appendix of white paper arXiv:1204.5379

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Summary:

Perspectives for LENA? LENA interesting recipient for a superbeam

[possibly beta beam, dep. on location]Robust wrt systematical errors for CERN-PyhäsalmiRobust on beam side? [0.8 MW vs. 4 MW]Similar performance for all values of CP

Mass hierarchy measurement certainly possible Comparison to alternatives (e.g. liquid argon)

depends on Fiducial mass for same budget? Neutral current BGs versus efficiency Event migration (status?)

Yet to little information for conclusive statements?

BACKUP

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CERN-LENA: def. systematics

Fiducial mass/ efficiency more important than backgrounds

(special thanks: Pilar Coloma)

100 kt liquid argon

100 kt LENA

90% eff.10% NC

50 kt LENA

90% eff.10% NC

50 ktLENA

90% eff.30% NC

50 ktLENA

50% eff.10% NC

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Impact of near detector

(Coloma, Huber, Kopp, Winter, in preparation)

(defaultsystematics)

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Comparison to eff. syst.

(Coloma, Huber, Kopp, Winter, in preparation)

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Systematics impact

(Coloma, Huber, Kopp, Winter, in preparation)

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Summary of options

(from: Coloma, Donini, Fernandez-Martinez, Hernandez, 2012)

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Beams: Appearance channels

(Cervera et al. 2000; Freund, Huber, Lindner, 2000; Akhmedov et al, 2004)

Antineutrinos: Magic baseline:

L~ 7500 km: Clean measurement of 13 (and mass hierarchy) for any energy, value of oscillation parameters! (Huber, Winter, 2003; Smirnov 2006)

In combination with shorter baseline, a wide range of very long baseline will do! (Gandhi, Winter, 2006; Kopp, Ota, Winter, 2008)

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Mass hierarchy discovery?

90% CL, existing equipment

3, Project X and T2K with proton driver, optimized neutrino-antineutrino run plan

Huber, Lindner, Schwetz, Winter, JHEP 11 (2009) 44

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Matter effect (MSW) Ordinary matter:

electrons, but no , Coherent forward

scattering in matter: Net effect on electron flavor

Hamiltonian in matter (matrix form, flavor space):

Y: electron fraction ~ 0.5

(electrons per nucleon)

(Wolfenstein, 1978; Mikheyev, Smirnov, 1985)

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Parameter mapping

Oscillation probabilities invacuum:matter:

Matter resonance: In this case: - Effective mixing maximal- Effective osc. frequency minimal

For appearance, m312:

- ~ 4.7 g/cm3 (Earth’s mantle): Eres ~ 6.4 GeV- ~ 10.8 g/cm3 (Earth’s outer core): Eres ~ 2.8 GeV

Resonance energy:

MH