Prospects in Neutrino Oscillation Experiments

Takaaki KajitaInstitute for Cosmic Ray Research, The Univ. of Tokyo

NuPhys2019London, UK

Dec. 16, 2019

Outline

• Introduction: Present Status• Neutrino Mass Ordering • CP violation • Other oscillation studies• Appendix: Proton decay• Status of next generation experiments• Summary

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Introduction: Present status

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Some of the new results at NNN 2019 (Nov. 2019)Super-K atmospheric (L. Wan) T2K (L. Pickering) NOvA (E. C. Mur)

Already some interesting indications: NO favored by these 3 experiments at ~(1 ~ 2) sigma level each. These experiments give some favored δCP region(s).

Normal

Inverted

Best fit

NOIO

NO

arXiv:1910.03887

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(w/o SK atm)(with SK atm)

Global fit (example)I. Esteban et al., JHEP 1901 (2019) 106

NO favored. Suggested δCP

range(s)

Agenda for the future neutrino measurements

(taken from R. B. Patterson, Ann Rev Nucl Part Sci 65 (2015) 177-192.)

Neutrino mass ordering?

)()( βαβα νννν →≠→ PP ?

CP violation?

Baryon asymmetry of the Universe?

Neutrinolessdouble beta decay

Beyond the 3 flavor framework?(Sterile neutrinos?)

Are neutrinos Majoranaparticles?

Absolute neutrino mass?

http://wwwkm.phys.sci.osaka-u.ac.jp/en/research/r01.html

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Next generation neutrino oscillation experiments

J-PARC

Hyper-KamiokandeDUNE

1300km

40 kton L.Ar TPC

190 ktonWater Ch

JUNO20 kton Liq. Sci.

+ some other experiments

Neutrino Mass Ordering

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Future experiments that will tell us the neutrino masses ordering

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DUNE

KM3NeT/ORCA

PINGUINO

Hyper-K

JUNO

Very good to have many projects for the MO measurements.We would like to be convinced the neutrino mass ordering by consistent results from several different technologies/methods with > 3 σ CL from each exp.

Masses ordering: DUNE

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Mass ordering at 5σ in 2-3 years of beam!

DUNE is very sensitive to MO thanks to very long baseline (matter effect). S. Prince, NNN2019

Masses ordering: JUNO

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Better than 3-4.5 sigma by a completely different method!

With T2K and Nova ∆m23

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W/O T2K and Nova

L. Miramonti, NNN2019

CP Violation

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Motivation

We would like to confirm that CP is violated in the neutrino sector.CP violation in the neutrino sector might be the key to

understand the baryon asymmetry of the Universe (Leptogenesis).…

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Next generation neutrino CPV experiments

J-PARC

Hyper-Kamiokande

We would like to observe if oscillation of neutrinos and those of anti-neutrinos are different.

DUNE

1300km

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Sensitivities

(M. Shiozawa, nu2018)Hyper-KDUNE

(E. Worcester, nu2018)

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ComplementarityDUNE Hyper-K

Baseline 1300km Large matter effect(Good for Mass Ordering determination)

295km Small matter effect(Smaller effect of matter density uncertainty in δCP)

Beam energy ~ Multi-GeV ~ Sub-GeV

Detector technology Liq. Ar TPC Water Cherenkov

We would like to be convinced the CP violation by the consistent results from these 2 experiments with very different systematics.

We hope that these 2 experiments will carry out the experiments in a similar timeline.

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After the initial CP results…DUNE (E. Worcester, nu2018) (M. Shiozawa, nu2018)Hyper-K

If the suggested CP phase by T2K, Super-K, and NOvA (IO) (around 3/2π or –π/2) is close to the real value, the determination of the CP phase angle will be rather poor. Should we better measure the phase angle? We would like to get inputs from theorists.

Other oscillation studies

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Precise measurements may tell us some hint for the physics beyond the SM.

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Solar neutrino oscillationsStatus of the 12-parameter measurements

S. Moriyama (Super-K), Neutrino 2016

~2σ tension

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Parameter determination: JUNO

Oscillation parameters

Current precision

JUNO

|∆m132| ~1.6% ~0.5%

∆m122 ~2.3% ~0.6%

sin22θ12 ~5.8% ~0.7%

L. Miramonti, NNN2019

JUNO will measure the 3 Oscillation parameters at a sub-percent precision level.

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Day-night effect: Hyper-KDay-night asymmetry sensitivity

(From no Day-Night asymmetry)

KamLAND best fit

Solar best fit

(BG syst. 0.1%)

BG syst. 0.3%

SK day/night

Kam

LAN

D

Sola

r Glo

bal

SK day/night and ∆m122

Super-K, PRL 112, 091805 (2014)

Day-night effect is one of the keys; to understand ∆m12

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to confirm the standard matter effect

Appendix: Proton decay

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Motivation

It is clear that proton decay is very important for understanding of physics at the very high energy scale (GUTs).Neutrino masses/mixings and proton decays might be

related to the physics at very high energy scale.

We are in an extremely interesting era. New large neutrino detectors (JUNO, DUNE and Hyper-K) will begin the operation in the near future. These detectors are also very good proton decay detectors.Therefore, we should not forget the proton decay searches in

the next generation “neutrino experiments”.

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Sensitivities

Hyper-K

DUNE 40kton

p→e+π0 3σ discovery

1035

1034

1033

Prot

on li

fetim

e [y

ears

]

2020 2030 2040 years

Super-K

p→νK+ 3σ discovery

Hyper-K

DUNE 40kton

SKJUNO

DUNE arXiv:1601.05471HK arXiv:1805.04163v1JUNO arXiv:1507.05613

(Lines for DUNE and JUNO experiment have been generated based on numbers in the literature.)

3σ discovery potential, if τp < 1035 years (eπ0) or < 5*1034 years (νk+)

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Key plots for confirming p e π 0

● “Free” proton decay● proton decay in Oxygen

In order to reach 1035 years, “free” proton decay (from Hydrogen) is very important!

(Hyper-K, arXiv:1805.04163v1)

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Key plots for confirming p e π 0

τproton=1.7×1034years (SK limit)

10 years Signal

Invariant Proton Mass (MeV/c2)

p→e+π0 Invariant Mass

background

(Hyper-K, arXiv:1805.04163v1)

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Key plots for confirming p ν K +

τproton=6.6×1033years (SK 90% CL limit)

(arXiv:1805.04163v1)

BG

Signal

JUNO

Hyper-K DUNEJHEP04(2007)041

Evidence for the stopped K+ decay…

We want to confirm that the Kaon momentum is consistent with proton decay.

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Other physics topics...

• Supernova neutrinos (in particular νe in DUNE, νx in JUNO, and anti-νe Hyper-K)

• Supernova relic neutrinos (JUNO and Hyper-K)• Geo-neutrinos (JUNO)• Atmospheric neutrinos (All) • Sterile neutrinos• …

Status of the next generation experiments

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Timeline: JUNO

JUNO will start taking data in 2021!

L. Miramonti, NNN2019

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Timeline: DUNE2017 Groundbreaking S. Prince, NNN2019

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Timeline: Hyper-KF. Di Lodovico, Nu2016In 2016 …

• But the project did not start in 2018…• Then the President of the Univ. of Tokyo pledged in 2018 to ensure construction of the Hyper-

Kamiokande detector commences in April 2020.• Budget request to begin Hyper-K in FY2020 (Apr. 2020) from MEXT to MoF in Aug. 2019.• On Dec. 13, 2019, the Japanese Cabinet has proposed the supplementary budget for FY2019. It

includes the budget for the construction of Hyper-K. (The approval will be made in ~Jan. 2020 in the Diet.) The project will start early 2020. The experiment will start in ~2027!

Summary

• In the last 2 decades, neutrino physics had a great progress.• However, many important questions are still unanswered.• We need the next generation experiments to answer the

unanswered questions. • The next generation experiments are very sensitive to

various important physics.• JUNO, DUNE and Hyper-K will start data taking in 2021,

2026(beam) and 2027, respectively.• We are extremely interesting era in neutrino physics!

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