Experimental Froniers in Nucleon Decay

Experimental Froners 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 Starng me? Guess 1 decade from now. by Super-K before next Adjust starng 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 scinllator 30,000 PMTs

3 How to improve exisng analyses v Sensivity 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 sensivity) 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 reconstrucon of EM showers. 1042-1052 1052-1062 1062-1072 1072-1082 1082-1092 Eﬃciency ∼45% dominated by >1092 0 670 nuclear absorpon of π 536 402 268 Low background ∼0.2 events/100 ktyr in SK 134 0 0 500 1000 1500 2000 Times (ns) Relavely insensive 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 beer 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 (dottedConnual 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 interacon 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 reconstrucon (“all new” is in the works) Atmospheric neutrino ﬂux, cross secon

8 Background Reducon 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 addion 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 Producon 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 Producon 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 Anlepton + 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 parcular 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 fracon 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 anlepton + meson modes (B-L)* 7 anlepton + 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 violaon 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

• exisng 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 verces K+ K-like parcle 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

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, beer 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 Scinllator: 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 scinllator (FV) • 32m x 100m • 30000 PMTs (30% with Winston cones) • Water Cherenkov veto

p ⟶ ν K+ Eﬃciency esmate ∼ 65% Background rate ∼ 1/yr/50 kton

Astroparcle Physics 35 (2012) 685–732 22 LENA

Energy Response Residual Timing Distribuons (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. 24 LBNE GLACIER/LBNO

v Two very diﬀerent technical designs – which is best? v Validate the 97% eﬃciency assumpon, as well as low BG v Essenal to get LBNE underground, and with no beam trigger v At least 20 kton is preferred – proton decay needs MASS.

25 What Other Modes are Good for LAr? v Modes with charged kaon in p →µ+ K0 ﬁnal state v Modes with displaced verces ⇒ v Mul-prong modes with no neutrino v Lepton + light meson are no beer than water due to nuclear absorpon of the light meson.

26 What Other Modes are Good for LAr? (2)

Super-K Water Ch. LAr (generic) Mode Eﬃciency BG Rate Eﬃciency BG Rate (/Mt y) (/Mt y) e+π0 45% 2 45% 1 B-L ν K+ 16% 7 97% 1 µ+ K0 10% 5-10 47% <2 µ- π+ K+ ? ? 97% 1 B+L e- K+ 10% 3 96% <2 ΔB=2 n nbar 12% 260 ? ? Rough and unofficial A. Bueno et al. SK efficiency & BG - ETK hep-ph/0701101

27 Soudan Frejus Kamiokande IMB Super-K (2012) Hyper-K p e+ 0 1 2 3 4 minimal SU(5) minimal SUSY SU(5) p e+ 0 predictions flipped SU(5), SO(10), 5D SUSY SU(5)

p e+ K 0 p + K 0 n K 0 LAr10 LAr20 LENA p K + 1 2 3 4

minimal SUSY SU(5) SUGRA SU(5) p 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 /B (years) 10 year exposures 28 Conclusion v The froner is, for now, deﬁned by further SK running, improvements, and new analyses v The next generaon experiment is needed to gain an order of magnitude in nucleon decay sensivity v The movang factors are as strong as ever v The movaon could become stronger with v Clear signs of SUSY at the LHC v Candidate events at SK v Serious reducon in cost to do the experiment

29 EXTRA

30 Neutron Anneutron Oscillaon

π0 γ γ π- 0 π γ γ π+ π+ γ π0 γ

v Created anneutron annihilates with nearby nucleon v About 2x nucleon mass is released as pions v Final states may be predicted from annihilaon data

31 Super-Kamiokande nnbar Result 2000 (a) Signal MC arXiv:1109.4227 1500 12 % +- 3% detecon eﬃciency 1000

500 BG Interacons:

20000 CC 1π : 27.2% (6.5 evt) (b) Atmospheric neutrino MC 1500 24.1+-5.8 background events NC 1π : 4.1% (1.0 evt) 1000

500 CC mπ : 32.5% (7.8 evt) 20000

Total Momentum (MeV/c) (c) Data NC mπ : 25.4% (6.1 evt) 1500

1000 24 candidates 32 Tbound > 1.89 10 years 500 ⇥ Tbound 0 ⌧free = 23 1 0 250 500 750 1000 1250 1500 1750 2000 r1 10 s ⇥ 8 Invariant Mass (MeV/c2) =2.4 10 s ⇥ 32 Iron Calorimeters (Get a feel for how a Lar TPC analysis might proceed)

simulaon candidate

Soudan 2: LAr compared to Iron Calorimeters: - hand scan - can do beer than requiring nch >= 4 - require n-charged ≥ 4 - eliminate protons, LAr compared to WC muons - can resolve recoil proton, charged - kinemac cuts current lepton

Back of the envelope esmate suggests even 10 kton LAr can do x10 beer than SK 33 EXTRA EXTRA

34 Pure speculaon… 1 Mton High density proton decay 44 strings 1 m x 5 m spacing cylinder in ice 70 m diameter 350 m height 4% PMT coverage 15000 PMTs

DeepCore

PINGU IceCube

35 ~ 1 pe/MeV Example event IceCube published scaering parameters

Hit Map Time Map 150 150

100 100

50 50

0 0

-50 -50

-100 -100

-150 -150

0 20 40 60 80 100 120 140 160 180 200 220 0 20 40 60 80 100 120 140 160 180 200 220

Chris Kachulis Graduate student 36