Experimental Fron/ers in Nucleon Decay Ed Kearns, Boston University froner Hyper-K 10 35 LAr20 LAr10 10 34 Super-K 10 33 Lifetime Sensitivity (90% CL) IMB 10 32 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 Year ∼ 0.5 Mt yr exposure Star/ng /me? Guess 1 decade from now. by Super-K before next Adjust star/ng /me as you wish. generaon experiments 2 What moves us towards the froners? v Connue exposure v Improve analysis Super-K v Search in new channels v Next generaon experiments • Detector R&D NNN • Experiment proposals Hyper-Kamiokande 560 kton water cherenkov 99K PMTs (20% coverage) LBNE 10/20 kton LAr TPC surface/underground? GLACIER/LBNO 20 kton LAr TPC 2-phase LENA 51 kton liquid scin/llator 30,000 PMTs 3 How to improve exis/ng analyses v Sensi/vity is based on: v Achieve: higher efficiency, lower background rate v Also important: improve accuracy of model (signal and/or BG) (which may increase or reduce sensi/vity) v Also: reduce systemac uncertainty v None of this is easy – gains will be small and hard fought v Increased exposure – gains are now minimal 4 Super-Kamiokande I Time(ns) < 952 952- 962 962- 972 972- 982 982- 992 992-1002 1002-1012 Simple signature: back-to-back 1012-1022 1022-1032 1032-1042 reconstruc/on of EM showers. 1042-1052 1052-1062 1062-1072 1072-1082 1082-1092 Efficiency ∼45% dominated by >1092 0 670 nuclear absorp/on of π 536 402 268 Low background ∼0.2 events/100 ktyr in SK 134 0 0 500 1000 1500 2000 Times (ns) Relavely insensi/ve to PMT density. 5 SK-I SK-II SK-III SK-IV 1000 PDK MC PDK MC PDK MC PDK MC 500 1000 ATM MC ATM MC ATM MC ATM MC 500 1000 Data Data Data Data SK 1+2+3+4 34 Total momentum (MeV/c) 500 τ/B > 1.3 x 10 yr PhysRevD.85.112001 0 0 1000 1000 1000 1000 Invariant proton mass (MeV/c2) 6 Efficiency and Background EFFICIENCY SK1 SK2 SK3 SK4 e+π0 44.6 ± 0.7 % 43.5 ± 0.7 % 45.2 ± 0.7 % 45.0 ± 0.7 % µ+π0 35.5 ± 0.7 % 34.7 ± 0.6 % 36.3 ± 0.7 % 43.9 ± 0.7 % • Determined by Super-K proton decay Monte Carlo simulaon • Lower efficiency for µ+π0 is due to required decay electron tag, but effect of beier electronics in SK4 can be seen BKG RATE (ev/Mt y) SK1 SK2 SK3 SK4 e+π0 2.1 ± 0.5 2.2 ± 0.5 1.9 ± 0.5 1.6 ± 0.4 µ+π0 2.6 ± 0.5 2.1 ± 0.4 2.6 ± 0.5 3.6 ± 0.5 • Background rate checked using K2K near detector: ++0+0.420.45 e π BG = 1.63-0.33 (stat)− 0.51 (sys.) evts/Mt⋅ yr PHYSICAL REVIEW D 77, 032003 (2008) 7 QE Differential Cross Section • Angular distribution for QE Total Crossscattering Section in ModificationSGPI is too forward a.u. peaked • In SGPI, parameterization given by Carroll et al. [Phys. Cross-check of SGPI input Rev. C 14, 635, (1976)]• wasSGNUCEFF used (solid(NEUT) line) has good agreement function • For the new fit (dottedCon/nual Improvements line), lower energy data was d 1 2 S 50, P 250 MeV/c exp CM included [Phys. SGPIRev. C Model: 53, 1745, (1996)] 2 E.g. Pion interac/on Monte Carlo (NEUT) – d 2 S S 25, P 250 MeV/cintranuclear scaering +-16O Cross Sections cm Old new New 213 MeV/c 353 MeV/c lab May 19, 2012 Pion Secondary Interactions Systematic Error Lab angle 17 May 19, 2012 Pion Secondary Interactions Systematic Error 15 Also: Detector simulaon tuning Improved reconstruc/on (“all new” is in the works) Atmospheric neutrino flux, cross sec/on 8 Background Reduc/on Strategies 1000 v 900 e+π0 proton decay MC Tight Cuts on Free Proton 800 700 - efficiency ~ 17% 600 - BG 0.015 evts/100 kton yr 500 - change over around 10-20 Mton yr 400 300 200 v Gadolinium otal momentum (MeV/c) T 100 - high energy neutrino events 0 0 200 400 600 800 1000 1200 n 2 are accompanied by Invariant proton mass (MeV/c ) - assume proton decay is not accompanied by n * surely not for free proton * also not for γ-tag states - consider Gd addi/on to WC to increase n-capture tag efficiency M. Shiozawa NNN09 - Gadolinium R&D underway at SK 9 Nuclear Physics of Proton Decay in 16O Spectroscopic factors measured in 16O(e,ep)15N experiment Gamma-ray emission measured in 16O(p,2p)15N experiment H. Ejiri Phys. Rev. C48 (1993) 10 Neutron Produc/on Study Background events Background event fractions 1 4000 LBNE-doc-3309, Jen Raaf CC, no neutrons 3500 0.8 3000 NC with no neutrons NC, no neutrons NC with proton & neutron 2500 NC with neutron 0.6 CC with no neutrons CC with proton & neutron 2000 CC with neutron 0.4 1500 NC, proton & neutron(s) 1000 0.2 500 NC, neutron(s) 0 0 0 100 200 300 400 500 600 700 800 900 1000 0 100 200 300 400 500 600 700 800 900 1000 Reconstructed 0 momentum (MeV/c) Reconstructed 0 momentum (MeV/c) SK Atmospheric neutrino single π0 events 46% of background events with neutrons Direct background to n → π0 ν Related process to backgrounds for p → e+ π0 11 Neutron Produc/on with ν: Experiments SK4 Preliminary Efficiency corrected n yield • New SK electronics (SK4 only) allows search for neutron associated with atmospheric neutrinos (capture on free proton, 2.2 MeV γ). • Other current, near future, and recent past experiments can also search. T2K, SciBooNE e.g. Capture /me 0-500 µs) • Dedicated new experiment (ANNIE) under discussion. 12 An/lepton + Meson Two-Body Modes Soudan Frejus Kamiokande IMB Super-K p e+ 0 1 2 3 4 n e+ - p + 0 n + - p + n 0 p e+ p + n p e+ 0 n e+ - p + 0 n + - p + n 0 p e+ p + n p e+ K 0 n e+ K - n e- K + p + K 0 n + K - p K + n K 0 p e+ K*(892)0 p K*(892)+ n K*(892)0 32 33 34 35 10 10 10 10 /B (years) 13 CASE STUDY: Using inclusive searches to constrain a par/cular model SUSY SO(10), B-L broken by 126-Higgs† H.S.Goh, R.N.Mohapatra, S.Nasri, S-P. Ng, Phys Lett B587:105-116 (2004) • predicts neutrino mixing well • scan over parameter space – find unconstrained branching frac/on o maximize n → ν π0 o N.B.: old ν K+ limit used as fixed constraint Super-K limit SUSY SO(10) predictions, Goh et al. p K + p e+ K 0 p + K 0 p + n 0 p e+ 0 p + 0 n K 0 32 33 34 35 36 10 10 10 10 10 /B (years) 14 × 1030 years 13000 SK1+2+3+4* ... 1600 SK1+2+3** ... 4000 SK1+2+3+4 preliminary ... 22 an/lepton + meson modes (B-L)* 7 an/lepton + mesons (3-body) modes * H. Nishino et al. Phys.Rev.D.85.112001 (12 modes) ** C. Regis et al. Phys.Rev.D.86.012006 (KS + KL) 12 lepton + meson modes (B+L)*** 16 more exclusive modes 5 inclusive modes 13 dinucleon decay modes Q: What other modes ! *** Super-K preliminary n ⟶ e- K+ τ/B > 9.9 × 1032 yr (90% CL) are interesting? ! 15 CASE STUDY: Dinucleon Decay pp ⟶ K+K+ Allow R-parity viola1on to reduce fine-tuning† † L. Carpenter, D.E., Kaplan S.Nasri, E. Rhee," • allows one to sneak in a light Higgs hep-ph/0607204v3 • avoid fast proton decay by allowing B-violaon only and not also L violates Lepton number violates Baryon number • exis/ng constraints on coupling λ’’ taken from dinucleon decay (!) v These limits are per Fe nucleus, from Frejus experiment, circa 1991 v No searches for NN→KK 16 K+ K+ (back-to-back) µ+ µ+ µ+ K+ are above Cherenkov ν threshold (p ≈ 800 MeV/c) K+ Displaced ver/ces K+ K-like par/cle ID ν µ+ 17 Dinucleon Decay pp ⟶ K+K+ Results Super-K Preliminary SK1 Data 7 Atm. MC 6 pp K+K+ MC 5 oxygen years 33 4 10 3 2 1 events / 3.06 M. Litos, Ph.D. thesis 0 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 boosted decision tree output τ/B > 1.7 × 1032 years (90% CL, SK1) -9 λ’’112 < 8 x 10 Two orders of magnitude smaller than limit inferred! from Frejus results (non KK): Goity & Sher, PLB346 (1995)! 18 Hyper-Kamiokande Next Generaon Nucleon Decay Detectors Hyper-K A Hyper-K B Fiducial Mass LENA Frejus Soudan 2 20 kt LAr Kamiokande Icarus T600 IMB Super-K 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 19 ν d τ˜ τ H˜ u t˜ € s SUSY, beier gauge unificaon € € D=5 operator u € u € Water: charged kaon below Cherenkov threshold but € € 16O gamma can be used to tag in WC (ε ∼ 16% for 2 low BG kaon modes) € € Liquid Scin/llator: Kaon decay energy and /me well measured in LS (ε ∼ 65%) LAr TPC: Charged kaon leaves track with correct dE/dx (ε ∼ 97%) 20 νK+ in Water Cherenkov 6 MeV gamma tag Qbk Qres γ-tag and π+π0 SK1 SK2 SK3 SK4 Efficiency 13.7 % 11.1 % 13.9 % 16.1 % Background rate (/Mt y) 6.7 ± 0.7 8.3 ± 0.8 5.7 ± 0.8 8.0 ± 0.8 No candidates, 220 kton yr (SK 1+2+3+4): 21 LENA Low Energy Neutrino Astronomy • 51 kt liquid scin/llator (FV) • 32m x 100m • 30000 PMTs (30% with Winston cones) • Water Cherenkov veto p ⟶ ν K+ Efficiency es/mate ∼ 65% Background rate ∼ 1/yr/50 kton Astropar/cle Physics 35 (2012) 685–732 22 LENA Energy Response Residual Timing Distribu/ons (single events) + + Κ →µ ν τK ~ 18 ns Κ+→π+π0 • 200 photoelectrons/MeV (40x Super-K) τK ~ 5 ns 23 νK+ in LAr simulated real Bueno et al.