Japan-based neutrino programMasato Shiozawa (UTokyo)

Super-K talk by Y.Suzuki,K2K/T2K talk T.Nakaya, T2K talk by A.Izmaylov,

Super-K talk by M.Shiozawa, Hyper-K talk by G.Catanesi,

Kamland-Zen talk by J.Shirai, @this workshop

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Super-K, 22kton Fid. mass

Hyper-Kamiokande2026~, 190kton mass, >1.3MW beam

J-PARC 470kW beam (T2K)

SK-Gd(201X~) J-PARC >750kW (T2K-II)

• Seamless program to get timely results • Rich physics, big chance of discoveries

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600 800 1000 1200Total invariant mass (MeV/c2)

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Proton decay (p→e+π0) search• Single event discovery is still possible in Super-K• Hyper-K is only realistic approach to proton lifetime beyond 1035 years

Hyper-K 10 years

0"<"ptot"<"100"MeV/c"�

p→e+π0 signal (τp=1.7 x 1034 years)

Invariant Proton Mass (MeV/c2)

~9σ discovery

Atmospheric ν background

• ~10MeV ν astronomy w/ essential information of (1)ν’s direction, (2)time, and (3)energy•w/ High mass (22kton→190kton)

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Neutrino astrophysics/astronomy

• Unique solar νe to study ~2σ tension btw νe and reactor νe

• Supernova ν burst up to ~Mpc distance to study explosion mechanism and BH/NS formation. Capability to provide SN direction w/ ~1o accuracy for alerting other telescopes including γ/GW observatory.

• SN diffuse ν to investigate dim-SN's and BH formation. Chance of discovery at SK-Gd and measurements in Hyper-K.

Filter tanksGd loaded water tank

New water system under construction

~1o Pointing (Center of Galaxy)

Diffuse SN ν at HK

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• T2K suggests |sinδCP|=1 and aims to discover w/ 3σ.• Big chance of CP violation discovery, and then measurement w/ precision of < 20 degree in HK.

year

Expected CPV significance

(Based on DUNE CDR, arxiv:1601.05471 Table 2.1, “optimized” beam design)

(2tank staging)

2022 2026 2030 2034 20380

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CPV significance for δ=-90°, normal hierarchy

Sign

ifica

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HK

DUNE

T2K

T2K-II

NOvA

2-Tanks

SK suggests normal hierarchy w/ ~2σ, further improvements are foreseen.Determination possible by 2~3 years (sin2θ23=0.5) at HK.

Mass hierarchy determination

BandforCPvalues

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νµ

νe

•Japan-based neutrino program will have rich physics with world-leading science outputs•Hyper-Kamiokande is the flagship experiment in the program

• Ready-to-go design

• Budget request is being issued in Japan

•Open for international participants• Many places where international contributions

(intellectual/in-kind) are necessary

Final remark

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