Overview of Hyper-Kamiokande
Masato Shiozawa ANT11 Workshop, Oct.-10-2011
Kamioka Observatory, Institute for Cosmic Ray Research, U of Tokyo, and Kamioka Satellite, Institute for the Mathematics and Physics of the Universe, U of Tokyo Establish θ13, then CP violation T2K collaboration, PRL107,041801(2011) Fogli et al., arXiv1106.6028
T2K observed indication of νμ→νe titled “Evidence of θ13>0 from global ν analysis”
Data ν Osc. e CC ν ν MeV) μ+ μ CC 3 ν e CC NC
2 Nobs : 6 νe candidates Nexp : 1.5±0.3(syst) 2 for sin 2θ13=0 1 nonzero θ13 at 2.5σ Number of events /(250 events of Number 0 0 1000 2000 3000 ν Reconstructed energy (MeV) nonzero θ13 is already >3σ w/ solar and reactorν
‣T2K aims to establish nonzero θ13 and measure it w/ more data ‣reactor experiments are starting data taking (Double CHOOZ, RENO, Daya Bay)
It’s now time to seriously think about next generation 2 experiments assuming θ13≠0 (sin θ13= a few %). Hyper-K WG, arXiv:1109.3262 [hep-ex] Letter of Intent: The Hyper-Kamiokande Experiment — Detector Design and Physics Potential —
K. Abe,12, 14 T. Abe,10 H. Aihara,10, 14 Y. Fukuda,5 Y. Hayato,12, 14 K. Huang,4 A. K. Ichikawa,4 M. Ikeda,4 K. Inoue,8, 14 H. Ishino,7 Y. Itow,6 T. Kajita,13, 14 J. Kameda,12, 14 Y. Kishimoto,12, 14 M. Koga,8, 14 Y. Koshio,12, 14 K. P. Lee,13 A. Minamino,4 M. Miura,12, 14 S. Moriyama,12, 14 M. Nakahata,12, 14 K. Nakamura,2, 14 T. Nakaya,4, 14 S. Nakayama,12, 14 K. Nishijima,9 Y. Nishimura,12 Y. Obayashi,12, 14 K. Okumura,13 M. Sakuda,7 H. Sekiya,12, 14
12, 14, 3 12, 14 12, 14 3, 14 M. Shiozawa, ∗ A. T. Suzuki, Y. Suzuki, A. Takeda, Y. Takeuchi, H. K. M. Tanaka,11 S. Tasaka,1 T. Tomura,12 M. R. Vagins,14 J. Wang,10 and M. Yokoyama10, 14
(Hyper-Kamiokande working group)
1Gifu University, Department of Physics, Gifu, Gifu 501-1193, Japan
2High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan
3Kobe University, Department of Physics, Kobe, Hyogo 657-8501, Japan
4Kyoto University, Department of Physics, Kyoto, Kyoto 606-8502, Japan
5Miyagi University of Education, Department of Physics, Sendai, Miyagi 980-0845, Japan
6Nagoya University, Solar Terrestrial Environment Laboratory, Nagoya, Aichi 464-8602, Japan
7Okayama University, Department of Physics, Okayama, Okayama 700-8530, Japan
8Tohoku University, Research Center for Neutrino Science, Sendai 980-8578, Japan
9Tokai University, Department of Physics, Hiratsuka, Kanagawa 259-1292, Japan
10 arXiv:1109.3262v1 [hep-ex] 15 Sep 2011 University of Tokyo, Department of Physics, Bunkyo, Tokyo 113-0033, Japan
11University of Tokyo, Earthquake Research Institute, Bunkyo, Tokyo 113-0032, Japan
12University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Gifu 506-1205, Japan
13University of Tokyo, Institute for Cosmic Ray Research, Research Center for Cosmic Neutrinos, Kashiwa, Chiba 277-8582, Japan
14University of Tokyo, Institute for the Physics and Math- ematics of the Universe, Kashiwa, Chiba 277-8583, Japan
(Dated: September 16, 2011)
1 8
TABLE II. Physics targets and expected sensitivities of the Hyper-Kamiokande experiment. σ is the Hyper-K WG, SD WIMP-proton spin dependent cross section. arXiv:1109.3262 [hep-ex]
Physics Target Sensitivity Conditions
Neutrino study w/ J-PARC ν 1.66 MW 5 years (1 year 107 sec) × ≡ 2 2 CP phase precision < 18◦ @ s 2θ ( sin 2θ ) > 0.03 and − 13 ≡ 13 mass hierarchy (MH) is known CPV 3σ discovery coverage 74% (55%) @ s22θ =0.1, MH known(unknown) − 13 ‣Baseline design 2 74% (63%) @ s 2θ13 =0.03, MH known(unknown) 2 of the Hyper-K 66% (59%) @ s 2θ13 =0.01, MH known(unknown) ‣physics potential Atmospheric neutrino study 10 years observation MH determination > 3σ CL @ 0.4 of 0.5 1.3eV/c2, and does not depend on whether the neutrino is a Dirac or Majorana particle. − Hyper-K is also capable of detecting supernova explosion neutrinos from galaxies outside of our own Milky Way; about 7,000-10,000 neutrinos from the Large Magellanic Cloud and 30-50 even from the Andromeda galaxy. Detection of supernova relic neutrinos (SRN) is of great interest because the history of heavy Hyper-Kamiokande candidate site ✦ 8km south from Super-K ✦ same T2K beam off-axis angle Mozumi Super-K ✦ 2.6km horizontal drive from entrance Mine ✦ under the peak of Nijuugo-yama ✦ 648m of rock or 1,750 m.w.e. overburden N ✦ 508m above sea level ~8km~10km ✦ dominated by Hornblende Biotite Gneiss and Tochibora Migmatite Mine ✦ 2.3km from waste rock disposal place ✦ 13,000 m3/day or 1megaton/80days natural water Hyper-K N 1,156m a.s.l. Candidate site 0M=845m a.s.l. overburden! 648m Hyper-K -300M Mine -370M Entrance 200m 508m a.s.l. -430M More on baseline design Geological survey Twin cavern analysis Concrete layer, polyethylene lining, PMT FEM analysis (Factor of safety) support Water system Gd loading test (Super-K collaboration) DAQ Photon sensor ADC+TDC network switch network Front End PC event builder with Software trig. switch 10 ev bld Total ~ 0.5 GB/s ~500 PMTs/FEPC /compartment ( / compartment ) ~20 FEPCs ~10MB/sec ( / compartment ) ( / compartment ) ~25 MB/s/FEPC Data flow manager Organizer TRG Front End PC GPS Front End PC To offline system 8’’ and 13’’ HPDs available in 2012 ( outside of the mine ) ! Hamamatsu will release in 2012 Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama 18 Physics targets ‣explore full picture of neutrino mass&mixing ‣explore unification picture of quarks and leptons ‣ J-PARC ν’s ‣ Discovery of Leptonic CP violation ‣ ν mass hierarchy ‣ Atmospheric ν ‣ supplemental information on ν properties ‣ Proton (or neutron) decays ‣ Solar ν ‣ Astrophysical objects ‣ Supernova burst ν and Supernova relic ν ‣ WIMP annihilation ν ‣ Solar flare ν, GRB ν, ... ‣ Neutrino Geophysics x25 Larger Target ~0.6GeV !µ" 295km Higher Intensity Quest for CP Violation >1.66MW (KEK roadmap) in lepton sector νμ→νe probability Normal hierarchy neutrino anti-neutrino 0.1 0.1 2 2 sin 2e13=0.1 sin 2e13=0.1 0.08 0.08 b= 0 b= 0 ) ) e = 1/2 b / e b= 1/2/ 0.06 b= / 0.06 Ai b= / Ai + = -1/2 + i b / b= -1/2/ 0.04 i 0.04 P( P( 0.02 0.02 0 0 0 1 2 0 1 2 Ei (GeV) Ei (GeV) − − ‣ CPV test by comparing P(νμ→νe) and P(νμ→νe) ‣ sensitive to exotic (non MNS matrix origin) CPV ‣ Fake CPV effect by matter effect 2 ‣ P(matter)/P(δ)~1/3 for sin 2θ13=0.1 2 ‣ P(matter)/P(δ)~1/10 for sin 2θ13=0.01 (pure δ-driven CPV) JPARC ν Near Far Detector target/ Decay volume Muon Detector (Super-K) Horn detector !" p ! off-axis proton on-axis 0 m π 11011 m 280 m 295 km 106 Neutrino run 106 Anti-neutrino run T T S R SR PO PO 5 5 21 21 10 SR 10 SR Se /10 /10 2 2 Se Se 104 104 Se 103 103 /50MeV/cm /50MeV/cm S S 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 ES (GeV) ES (GeV) ‣ J-PARC ν’s ‣ T2K flux based on beamline geometry, horn (320kA), hadron (π, K) production data, proton profile ‣ anti-ν by inverted horn current ‣ Quasi-monochromatic ν w/ peak energy at oscillation maximum ‣ intrinsic beam νe (BG) is <1% at peak energy Detailed study figures for 40% photo-coverage Super-Kamiokande IV Run 999999 Sub 0 Event 209 ν Full simulation of ν interaction, hadron 10-02-17:16:23:39 e ‣ Inner: 3136 hits, 6453 pe simulation CC Outer: 3 hits, 2 pe Trigger: 0x03 D_wall: 1218.7 cm secondary interactions (NEUT) e-like, p = 701.5 MeV/c Charge(pe) HK detector response by modified Super- >26.7 ‣ 23.3-26.7 20.2-23.3 17.3-20.2 14.7-17.3 12.2-14.7 K simulation 10.0-12.2 8.0-10.0 6.2- 8.0 e 4.7- 6.2 3.3- 4.7 PMT density 40%→20% 2.2- 3.3 ‣ 1.3- 2.2 0.7- 1.3 0.2- 0.7 light propagation, electronics response < 0.2 ‣ 1300 0 mu-e 1040 decays ‣ small geometry difference (~35m(SK) 780 520 260 ⇔50m(HK)) 0 0 500 1000 1500 2000 Times (ns) νe event selection Super-Kamiokande IV ! Run 999999 Sub 0 Event 458 NC 1π 10-02-15:01:36:54 Inner: 3366 hits, 8116 pe Outer: 7 hits, 5 pe simulation 1. Fully Contained & in Fiducial Volume Trigger: 0x03 0 D_wall: 1443.6! cm 0 "e-like, p = 898.6 MeV/c ! # small opening & Evis>100MeV angle Charge(pe) >26.7 23.3-26.7 20.2-23.3 2. 1-ring 17.3-20.2 14.7-17.3 12.2-14.7 10.0-12.2 8.0-10.0 6.2- 8.0 3. e-like 4.7- 6.2 3.3- 4.7 2.2- 3.3 1.3- 2.2 0.7- 1.3 4. No muon decays 0.2- 0.7 < 0.2 2 1400 0 mu-e 5. Minv < 100 MeV/c 0 1120 decays π →γγ 840 rec 560 6. E ν < 2 GeV (looser cut to use 280 0 0 500 1000 1500 2000 spectrum information) Times (ns) Selected νe candidates (and BG) 2 sin 2θ13=0.1, δ=0 S mode 1.66MW×1.5yrs S mode 1.66MW×3.5yrs 600 400 Total Total 300 SRqSe 400 BG all BG all 200 BG from SeSRSR BG fromS + S 200 BG fromSR R R Events/50MeV Events/50MeV 100 BG fromSR candidates e ν 0 0 0 1 2 0 1 2 rec rec ES (GeV) ES (GeV) νμ→νeCC: 3940 ev νμ→νeCC: 421 ev −νμ→ν−eCC: 51 −νμ→ν−eCC: 2168 νμ+−νμCC : 39 νμ+−νμCC : 25 νe+−νeCC :977 νe+−νeCC :972 NC :718 NC :750 νe signal efficiency ⇔ BG rejection 0 64% νμ+antiνμCC <0.1%, NCπ <5% rec (0.1 Total BG 200 Total BG SRSR BG 200 SRSR BG Events/50MeV Events/50MeV 100 candidates e 0 0 ν 0 1 2 0 1 2 rec rec ES (GeV) ES (GeV) 150 150 stat. error only I"U stat. error only I"U 100 I"U 100 I"U I"U I"U 50 50 0 0 =0 case =0 -50 -50 δ diff.from Events/50MeV Events/50MeV -100 -100 -150 -150 0 1 2 0 1 2 rec rec ES (GeV) ES (GeV) Contours Normal mass hierarchy (known) Hyper-K (540kt FV) / 1.5yrs i + 3.5yrs i!$1.66MW Hyper-K (560kt FV) / 1.5yrs d + 3.5yrs d /1.66MW 1 40 1m ѝ 2m 3m 30 ѝ # / T2K90%CL !" 0 20 b HUURURIѝ GHJUHH i 10 1 -1 0 0 0.02 0.04 0.06 0.08 0.1 0.12 0 0.05 0.1 2 2 sin 2e13 sin 2V13 Good sensitivity in whole T2K’s ‣δ precision < 18° (δ=90°) θ13 allowed region! < 8° (δ= 0°) ‣modest dependence on θ13 value If mass hierarchy is unknown ‣Normal hierarchy ‣m3 is heaviest ‣Inverted hierarchy ‣m3 is lightest Normal Inverted hierarchy hierarchy neutrino anti-neutrino 0.1 0.1 2 2 Solid: normal mass hierarchy sin 2V13=0.1 sin 2V13=0.1 0.08 0.08 Dashed: inverted mass hierarchy I= 0 I= 0 ) ) e = 1/2 I U e I= 1/2U 0.06 I= U 0.06 qS I= U qS R = -1/2 R S I U I= -1/2U 0.04 S 0.04 P( P( 0.02 0.02 0 0 0 1 2 0 1 2 ES (GeV) ES (GeV) Degeneracy may occur if mass hierarchy is unknown JHEP10,001(2001) If mass hierarchy is unknown Normal mass hierarchy (unknown) discrimination power of mass hierarchy Hyper-K (560kt FV) / 1.5yrs S + 3.5yrs S1.66MW Hyper-K (560kt FV) / 1.5yrs S + 3.5yrs S1.66MW 1 1 right solution 0 0 I@UB I@UB wrong solution 1X (due to wrong MH T2K90%CL 2X assumption) Mass Hierarchy unkown 3X (true: Normal Hierarchy) 3X -1 -1 0 0.02 0.04 0.06 0.08 0.1 0.12 0 0.05 0.1 0.15 2 sin22V sin 2V13 13 multiple solutions, wider allowed MH could be determined by region due to wrong MH assumption HK-JPARC experiment ‣Any improvement to resolve the degeneracy? Need more study. ‣Input (mass hierarchy) from other experiments may become important. ‣from Noνa? or ν-less DB? or... ‣One possibility is to determine MH by atm. ν study (discuss later) Fraction of δ (%) for CPV Fraction of δ in % for which expected CPV (sinδ≠0) significance is >3σ 100 2 sin 2e13= 0.1 0.03 MH known 0.01 MH unknown 80 60 40 1.66MW×5years )UDFWLRQRIѝ 20 560kton FV ѫ 0 1 2 3 4 5 6 7 8 9 10 ,QWHJUDWHGEHDPSRZHU 0:t\HDU CP violation can be observed with >3σ for 74% of the δ param. space. If MH is assumed to be unknown, it degrades to ~60%. Oscillated νe flux NuclPhysB680,479(2004) r : µ/e flux ratio (~2 at low energy)! ! 2 P2 = |Aeµ| : 2! transition probability !e ! !µ" in matter! * R2 = Re(A eeAeµ)! I = Im(A* A )! Solar term 2 ee eµ Aee : survival amplitude of the 2! system! Aeµ : transition amplitude of the 2! system! Interference term (!CP) "13 resonance term Oscillated νe flux Relevant ν oscillation parameters Non-oscillation ‣Solar term 2 ‣sin θ23 ‣Interference term ‣δ, matter effect (θ13, Mass Hierarchy) 1) ! 2 $23 ‣θ13 resonance term "sin 2 resonancem (r sin θ23, matter effect (θ13, Mass Hierarchy) $13 2 $13 ‣ sin # Effective θ13 becomes large due to Earth’s matter potential more νe appearance - happens in ν in the case of normal mass hierarchy - in anti-ν in inverted mass hierarchy νe-like and anti-νe-like sample 2 sin 2θ13=0.1 1.2 2 s23=0.4, inverted hierarchy − Upward νe 2 Normal s23=0.5, inverted hierarchy ν +N→e +X 2 e appearance s =0.6, inverted hierarchy 23 1.15 2 s23=0.4, normal hierarchy s2 =0.5, normal hierarchy − + 23 s2 =0.6, normal hierarchy νe+N→e +X 23 1.1 (b) Multi-GeV i -like Multi-GeV νe e-like 0 e /N + e 1.05 Inverted ‣ νe CC produce more π N ‣ more muon decays 1 ‣ More energy transfer to hadronic system 0.95 ‣ lower charged lepton energy 0.9 -like events -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 ‣ more pions (muon decays) e cos O 1.2 2 s23=0.4, inverted hierarchy 2 s23=0.5, inverted hierarchy 2 s23=0.6, inverted hierarchy 1.15 2 s23=0.4, normal hierarchy Non-oscillated 2 s23=0.5, normal hierarchy ‣ # of rings s2 =0.6, normal hierarchy enrichment by variables 1.1 23 ‣ # of muon decay electrons (c) Multi-GeV anti-− ie-like Oscillated Oscillated Multi-GeV νe-like ‣ Lepton energy fraction 0 e /N e 1.05 ‣ transverse momentum N 1 νe CC anti-νe CC others Total 0.95 νe-like 57% 11% 32.0% 100% 0.9 anti-νe-like 55% 34% 11% 100% -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 cos O Mass hierarchy discrimination power 50 50 sin2e = 0.4 sin22e = 0.04 sin2 = 0.4 sin22 = 0.04 23 13 e23 e13 sin2e = 0.4 sin22e = 0.08 sin2 = 0.4 sin22 = 0.08 23 13 e23 e13 45 sin2e = 0.4 sin22e = 0.16 45 sin2 = 0.4 sin22 = 0.16 23 13 e23 e13 sin2e = 0.5 sin22e = 0.04 sin2 = 0.5 sin22 = 0.04 23 13 e23 e13 2 2 sin e = 0.5 sin 2e = 0.08 sin2e = 0.5 sin22e = 0.08 40 23 13 40 23 13 =0.6 sin2e = 0.5 sin22e = 0.16 sin2 = 0.5 sin22 = 0.16 23 13 e23 e13 23 2 2 =0.6 2 θ sin e = 0.6 sin 2e = 0.04 sin2e = 0.6 sin22e = 0.04 35 23 13 23 35 23 13 sin2e = 0.6 sin22e = 0.08 2 θ sin2 = 0.6 sin22 = 0.08 sin 23 13 e23 e13 ) sin2e = 0.6 sin22e = 0.16 ) sin2 = 0.6 sin22 = 0.16 23 13 sin e23 e13 2 NH 30 2 NH 30 r r - Normal mass hierarchy - Inverted mass hierarchy 2 IH 2 IH r 25 HK fiducial mass: 560 kTon r 25 HK fiducial mass: 560 kTon ( ( 2 2 r r =0.5 =0.5 20 23 >3σ 20 23 >3σ 6 2 θ 6 2 θ sin sin 15 15 3 m 10 3 m 10 5 5 sin2θ23=0.4 sin2θ23=0.4 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 Hyper-K years Hyper-K years ‣expect to discriminate normal from inverted hierarchy w/ 3σ significance by ~5years data. 2 2 2 ‣If sin θ23 is as small as 0.4 or less, we may need >10years.(sin θ23=0.4 ⇔ sin 2θ23=0.96) ‣θ23 (and θ13) measurements in near future will make the sensitivity more accurate. θ23 octant 2 2 sin 2θ23=0.96 sin 2θ23=0.99 ↓ ↓ 2 2 sin θ23=0.4 or 0.6 sin θ23=0.45 or 0.55 0.3 Normal mass hierarchy 0.3 Normal mass hierarchy Hyper-K 10 years Hyper-K 10 years 90% C.L. 90% C.L. 0.25 No fake solutions 0.25 0.2 0.2 13 13 True e e 2 2 2 0.15 2 0.15 sin sin 0.1 0.1 0.05 0.05 0 0 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 2 sin2 sin e23 e23 2 If sin 2θ23<0.99, θ23 octant can be determined. δCP 0.18 0.18 0.18 0.18 Hyper-K 4 years 90% CL 0.16 0.16 0.16 0.16 99% CL 0.14 0.14 0.14 0.14 0.12 0.12 0.12 0.12 13 13 13 13 θ θ θ θ 0.1 0.1 2 0.1 0.1 2 2 2 0.08 0.08 sin 0.08 sin sin 0.08 sin 0.06 0.06 0.06 0.06 0.04 0.04 0.04 0.04 0.02 0.02 0.02 0.02 0 0 0 50 100 150 200 250 300 0 0 0 50 100 150 200 250 300 0 50 100 150 200 250 300 δcp 0 50 100 150 200 250 300 δcp δ cp δcp 0.18 0.18 0.18 0.18 0.16 0.16 0.16 0.16 0.14 0.14 0.14 0.14 0.12 0.12 0.12 0.12 13 13 13 13 θ θ θ θ 0.1 0.1 2 2 0.1 0.1 2 2 0.08 sin 0.08 0.08 sin 0.08 sin sin 0.06 0.06 0.06 0.06 0.04 0.04 0.04 0.04 0.02 0.02 0.02 0.02 0 0 50 100 150 200 250 300 0 0 0 δ 0 50 100 150 200 250 300 0 50 100 150 200 250 300 0 50 100 150 200 250 300 cp δ δ cp δcp cp Supplemental information on Dirac δ Nucleon decay searches Soudan Frejus Kamiokande IMB Super-K p A e+ /0 1 2 3 4 minimal SU(5) minimal SUSY SU(5) p A e+ /0 predictions ∅ flipped SU(5), SO(10), 5D SUSY SU(5) p A e+ K 0 p A ++ K 0 n A i K 0 p A i K + 1 2 3 4 minimal SUSY SU(5) SUGRA SU(5) p A i K + ∅ SUSY SU(5) with additional U(1) flavor symmetry predictions various SUSY SO(10) SUSY SO(10) with G(224) SUSY SO(10) with Unified Higgs 31 32 33 34 35 10 10 10 10 10 o/B (years) ‣Super-Kamiokande provides stringent limits for many decay modes. ‣τ(p→e+π0)>1.3×1034 years (90%CL w/ 220kton·years) ‣τ(p→νK+) >4.0×1033 years (90%CL w/ 220kton·years) ‣gives constraints on Grand Unification picture. ‣constraints on SUSY models e.g. R-parity conservation ‣excludes minimal SU(5), minimal SUSY SU(5). Next candidate is SUSY SO(10)? class of SUSY SO(10) GUT Babu et al. JHEP06(2010)084 ‣ Characteristics ‣ Low dimension Higgs: {45+16+16*+10} ‣ Avoid Triplet-Doublet problem ‣ Account for quark&lepton masses ‣ tiny neutrino mass←Seesaw mechanism ‣ Mixing←Q4 flavor symmetry ‣ Predicted decay rates M r = ! M X Both decays are reachable by Hyper-K. Super-K cut! ! 2 or 3 Cherenkov rings ! All rings are showering + 0 2 → ! 85 < M!0 < 185MeV/c (3-ring) p e +π searches ! No decay electron 2 ! 800 < Mproton < 1050 MeV/c Ptotal < 250 MeV/c Super-K data are well reproduced by BG MC. 1000 3 2 10 10 Super-Kamiokande 219.7SK1~4 ktyr exposure SK1~4 SK1~4 DST 800 2 10 2,3ring PID 0 10 / decay-e 600 1 10 M -1 tot 400 Signal Box 10 Atm. i MC Ptot (events/ktyr) Data Number of events 1 200 -2 Total momentum (MeV/c) 10 Signal Box -1 -3 0 10 10 0 200 400 600 800 1000 1200 0 200 400 600 800 1000 1200 ABCDE Invariant proton mass (MeV/c2) 2 Total invariant mass (MeV/c ) Selection criteria - detection efficiency = 45% - atmospheric ν BG = 2.1±0.3(stat.)±0.8(syst.) (Mton×years)-1 34 PRD77:032003,2008 - τproton/Br > 1.3 ×10 years @ 90%CL ‣ BG measurement by accelerator ν (K2K) ‣BG=1.63+0.42/-0.33(stat.)+0.45/-0.51(syst.) (Mt×yrs)-1 (Eν<3GeV) ‣Consistent w/ simulation 1.8±0.3(stat.) Quality of next generation search is guaranteed. Search for various decay modes - many models predicts branching ratio of p→e+η, e+ρ, e+ω are 10~20% - Flipped SU(5) (Ellis) predicts Br(p→e+π0)~Br(p→μ+π0) - (B-L) violated mode, e.g. |ΔB|=2. Soudan Frejus Kamiokande IMB Super-K Hyper-K Hyper-K sensitivities p A e+ /0 1 2 3 4 n A e+ /- p A ++ /0 p→e++π0 n + - ‣ A + / 35 p A i /+ ‣τproton/Br > 1.3 ×10 years @90%CL n A i /0 ‣5.6Mton×years (10 Hyper-K years) p A e+ d p A ++ d n A i d ‣p,n→(e+,μ+)+(π,ρ,ω,η) + p A e l0 34~35 n A e+ l- ‣O(10 )years p A ++ l0 n A ++ l- + p A i l+ ‣SUSY favored p→ν+K n A i l0 ‣2.5×1034 years p A e+ t p A ++ t 0 0 + n A i t ‣K modes, νπ , νπ possible p A e+ K 0 n A e+ K - n A e- K + ‣Other various decay modes. p A ++ K 0 n A ++ K - ‣(B-L) violated modes + + + p A i K ‣radiative decays p→e γ, μ γ n A i K 0 neutron-antineutron振動 (|ΔB|=2) p A e+ K*(892)0 ‣ + p A i K*(892) Δ n A i K*(892)0 ‣di-nucleon decays (| B|=2) 32 33 34 35 ‣pp→XX..., nn→XX... 10 10 10 10 o/B (years) Summary - Baseline design and physics potential are described for Hyper-K. - based on well proven technology (water Cherenkov) - discovery reach for leptonic CP violation. - precision measurement of neutrino property. - unprecedented sensitivity for nucleon decays. - astrophysical ν etc. - Next step: - Maximize (Physics sensitivity) / (cost) - New technology is a key to realize the project.