Neutrino oscillations: Perspective of long-baseline experiments

Neutrino oscillations: Perspective of long-baseline experiments

522. Wilhelm and Else Heraeus-Seminar:Exploring the neutrino sky and fundamental particle physics on the Megaton scale

Bad Honnef, Jan. 21, 2013

Walter WinterUniversität Würzburg

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Contents

Introduction Measurement of CP:

Experiments and phenomenology The critical issue for large 13:

Systematics? Long-baseline alternatives with new

technologies? Comment on sterile neutrinos Summary

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(also: T2K, Double Chooz, RENO)

(short baseline)

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Consequences of large 13

13 to be well measured by Daya Bay

Mass hierarchy: 3 discovery for up to 40% of all CP possible iff ProjectX, possiblyuntil 2025

CP violation measurement extremely difficultNeed new facility!

Huber, Lindner, Schwetz, Winter, 2009

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Mass hierarchy measurement?

Mass hierarchy discovery possible with atmospheric neutrinos? (liquid argon, HyperK, MEMPHYS, INO, PINGU, ORCA …)

Barger et al, arXiv:1203.6012;IH more challenging

NB: basically any new LBL experiment at design luminosity with E > 1 GeV and L >> 600 km can for all CP measure the hierarchy in e- transition (MSW effect)!

Alternative: medium-baseline reactor experiments, perhaps

Perhaps differentfacilities for MH and CPV

proposed/discussed?

Talks by Smirnov (2), Resconi, Heijboer

Measurement of CP:Experiments and phenomenology

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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 leptogenesis by decay of heavy see-saw partner?

Model building

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

Need performance which is equally good for all CP

Symmetrye.g. TBM, BM, …?

Correction leadingto non-zero 13?

sin

cos

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Antineutrinos: Problem: Earth matter violates CP, CPT explicitely!

Silver:Challenging ( threshold, many decay channels, vertex res.)

Platinum, T-inv.: Works only for Superbeam + Beta beam (later)

Long-baseline oscillations

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

Large!

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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

Possible LBL neutrino sources

Protons

Target Selection,focusing

Pions

Decaytunnel

Absorber

Neutrinos

Superbeam

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Example: Neutrino FactoryInternational Design Study (IDS-NF)

IDS-NF: Initiative from ~ 2007-2013 to present a design report, schedule, cost estimate, risk assessment for a neutrino factory

Vision? Staged approach towards high-energy frontier ( muon collider)

(Geer, 1997; de Rujula, Gavela, Hernandez, 1998; Cervera et al, 2000)

Signal prop. sin2213

Contamination magnetized detector!

Muons decay in straight sections of a storage ring

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The new paradigm: Precision?

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

indicators, e. g.Reveals that

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

Hernandez, 2012)

Bands: 13 allowed ranges

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

liquid argon

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Talk by Diwan

The critical issue for large 13:Systematics?

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Fluxes and cross sections: Superbeam, beta beam (illustrated)

Superbeam

Beta beam

Near detector

Disappearance

Appearance Fardetector

Flux F1

Near detector

Disappearance

Appearance Fardetector

Flux F2

?

?BB+SPL

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Fluxes and cross sections:Neutrino Factory

Muon (anti)neutrino cross sections measured in self-consistent way

Fluxes in and fully correlated

(Tang, Winter, PRD 80, 053001, 2009)

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The big unknown: Systematics

New treatment needed Use explicit near-far detector

simulations Use same knowledge for

cross sections for all experiments Define ranges for systematical

errors: optimistic-default-conservative

Use identical framework for systematics implementation/correlations Define reasonable ranges for experiment-dependent systematics:

(Coloma, Huber, Kopp, Winter,

arXiv:1209.5973)

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Long-baseline options

Setup table

(Coloma, Huber, Kopp, Winter, arXiv:1209.5973)

+ Daya Bay

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Precision:

Worldwide comparison

CKM phase

(bands: systematics

opt.-cons.)


The Neutrino Factoryis the only instrument

which can measure CP

with a precision comparableto the quark sector

NF10BB350WBBT2HK

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Interesting alternatives

Comparison at default systematics:


NF5 exhibitsstrong dependence on CP (some dependence on binning!)

BB100+SPL is the only setup comparable with NuFact

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Critical impacts?


Robust wrt systematics

Main impact:Matter density uncertainty

Operate in statistics-limited regime

Exposure more important than near detector orsystematics MICA?

Neutrino Factory

High-E superbeam

Low-E (QE!) superbeam

QE e X-sec critical:no self-consistent measurement

Theory: e/ ratio?Experiment: STORM?

Long-baseline alternatives with new technologies?

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Superbeam CERN-LENA?

Main impact factors:Neutral current

backgrounds versus efficiency

Fiducial volume (cost?)

To be studied?Background

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

Combination with liquid argon?

L ~ 2300 km

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

Talks by Wurm, Hellgartner

(special thanks: Pilar Coloma)

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Beam to South Pole?

Probability for L=11810 km (CERN/FNAL/JHF-South Pole)

(Parametric enhancement: Akhmedov, 1998; Akhmedov, Lipari, Smirnov, 1998; Petcov, 1998)

Core resonance

energy

Mantleresonance

energy

Param.enhance-

ment

Thresholdeffects

expected at:2 GeV 4-5 GeV

Naive L/E scalingdoes not apply!

Parametric enhancementthrough mantle-core-mantle

profile of the Earth.Unique physics potential!

!

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IceCube/DeepCore upgrades?

Fill in IceCube/DeepCore array with additional strings Drive threshold to lower

energies

PINGU (“Precision IceCube Next Generation Upgrade“): LOI in preparation

Modest cost ~30-50M$ (dep. on no. of strings)

Two season deployment anticipated: 2015/2016/2017

A megaton-class detector at a few GeV (param. enhancement)

Further upgrades being discussed (MICA)

(PINGU, 12/2012) Talks by Kowalski

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Example:

Low-intensity superbeam? Use existing equipment (Fermilab main injector),

new beam line Here: use most conservative assumption

NuMI beam, 1021 pot (total), neutrinos only[compare to LBNE: 22+22 1020 pot without Project X ~ factor four higher exposure than the one considered here] (FERMILAB-PROPOSAL-0875, NUMI-L-714)

Low intensity may allow for shorter decay pipe(< 600M$ ?)

Advantage: Peaks in exactly the right energy range for the parametric enhancement/core effect

M. Bishai

Pe

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Mass hierarchy: Event rates

Normal hier. Inv. hierarchy

Signal 1560 54

Backgrounds: e beam (irreducible) 39 59

Track mis-ID (20%) 511 750

appearance (below production threshold!)

3 4

Neutral currents (irred.) 2479 2479

Total backgrounds 3032 3292

Total signal+backg. 4592 3346

(Daya Bay best-fit)

>18 (stat. only)

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NuMI-like beam to PINGU?

Very robust mass hierarchy measurement (as long as either some energy resolution or control of systematics); no directional information needed

(Daya B

ay best-fit; current param

eter un

certainties, min

imized over)

GLoBES 2012

All irreducible backgrounds included

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Potential for CP?

NH

L=11810 km

Energy resolution prerequisite:

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Upgrade path towards CP?

Measurement of CP in principle possible, but challenging

Requires: Electromagnetic

shower ID (here: 1% mis-ID)

Energy resolution (here: 20% x E)

Volume upgrade(here: ~ factor two)

Project X Performance and

optimization of PINGU and MICA requires further study

= LBNE + Project X!

Tang, Winter, JHEP 1202 (2012) 028

same beamto MICA?

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Matter density measurementExample: LBNE-like Superbeam

Precision ~ 0.5% (1) on core density

Complementary to seismic waves

Tang, Winter, JHEP 1202 (2012) 028(Alan Jones, 1999)

Comments on sterile neutrinos

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Evidence for sterile neutrinos?

LSND/MiniBooNE Reactor+gallium anomalies

Global fits

Cosmology(M

iniB

ooN

E @

Neu

trin

o 20

12)

(B. F

lemin

g, TA

UP

2011)

(e. g. 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?) QE electron neutrino and antineutrino cross sections (T2HK!)

Example: STORM - Neutrinos from STORed Muons (LOI: arXiv:1206.0294) can do it all! Summary of options: Appendix of white paper arXiv:1204.5379

MiniBooNE

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Conclusions

The precision measurement of CP requires a new dedicated long-baseline experiment

Such an experiment can (typically) also measure the mass hierarchy; however, there are alternatives

The critical impact factors for CP are: Exposure (high-E superbeam) Electron neutrino cross sections

(low-E superbeam, beta beam) Matter density uncertainty (Neutrino Factory)

Alternatives require further study. Examples: Beam to South Pole (MICA?) Beam to LENA

BACKUP

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New performance indicator


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Impact of implementation Gray (eff. systematics, 0-10%) versus color (new):

More precise predictions for Neutrino Factory (bands: conservative – optimtistic, curves: default)

Systematic offset for T2HK, BB350 (QE e cross sec. issue)


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NuFact vs. BB+SPL


Near detectorsnot so important if

disappearance information from FD

and three-flavor framework valid

Exception: NF5(main impact)

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Mass hierarchy using existing equipment?

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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Neutrino oscillations: Perspective of long-baseline experiments