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Home , Proton decay

DUNE Scientific Opportunities and Capabilities for Decay Searches

Aaron Higuera University of Houston Conference on Science at the Sanford Underground Research Facility, SD, 2017 Outlook

• Introduction Gran Unified Theories and Proton Decay • LArTPCs • DUNE Experiment • Proton Decay Signatures at DUNE • Proton Decay Backgrounds at DUNE • Summary

Conference on Science at the Sanford Underground Research Facility, SD, 2017 3 The Standard Model of Elementary Particles

Proton

• Strong Force Quarks • Electromagnetic force Quarks Charged • Weak Force from Wikipedia Charged Leptons Neutrinos (neutral leptons)

Conference on Science at the Sanford Underground Research Facility, SD, 2017 4 The Standard Model of Elementary Particles

The Standard Model has been very successful

Predicted the existence of the W and Z , and the top and charm quarks before these particles were observed

Z mass prediction 91.1874 ± 0.0021 GeV/c2

from Wikipedia Z boson global fit (data) 91.1876 ± 0.0021 GeV/c2

Conference on Science at the Sanford Underground Research Facility, SD, 2017 5 The Standard Model of Elementary Particles

However, there are several questions remaining

• Why are there three interactions? • Why are there three generations? • Why neutrinos are so light compared to other leptons? • Why is the proton charge the opposite to the electron?

from Wikipedia

Conference on Science at the Sanford Underground Research Facility, SD, 2017 6 Grand Unified Theories

In order to solve those question Grand Unified Theories (GUTs) has been proposed

Standard Model GUT (Unified Force)

electromagnetic ~1016 GeV

weak

strong Weakness of force of Weakness Weakness of force of Weakness

Energy (GeV) Energy (GeV)

• Can we tested these theories? Impossible to reach this energy at the laboratory • A GUT combined with a symmetry SU(5) or distinguishes themselves from other GUTs theories • Prediction of proton decay

Conference on Science at the Sanford Underground Research Facility, SD, 2017 7 Grand Unified Theories

In order to solve those question Grand Unified Theories (GUTs) has been proposed

Standard Model GUT (Unified Force)

electromagnetic ~1016 GeV

weak

strong Weakness of force of Weakness Weakness of force of Weakness

Energy (GeV) Energy (GeV)

• Can we tested this theories? Impossible to reach this energy at the laboratory • Proton decay • Thus, proton decay is the key to unlocking the potential of these GUTs

Conference on Science at the Sanford Underground Research Facility, SD, 2017 8 Grand Unified Theories

• A GUTs based on SU(5) symmetry favored a proton decay channel p→ e+ π0 • The dominant channel in a SUSY GUTs p→ K+ ⊽ • There are many other decays models that have been proposed I would focus on the most explored

Figs: arXiv:1512.06148

Conference on Science at the Sanford Underground Research Facility, SD, 2017 9 Proton Decay

• This channel has straightforward experimental signature for a water Cherenkov detector • Where background-free high-efficiency searches are possible with large water Cherenkov detectors

• On the other hand this channel represents a challenge for water Cherenkov detectors because the kaon is below threshold • The key signature is the presence of an isolated charged kaon Figs: arXiv:1512.06148

Conference on Science at the Sanford Underground Research Facility, SD, 2017 10 Proton Decay & LArTPC

• LArTPC technology exhibits a significant performance advantage over the water Cherenkov technology • Charged particles ionize Ar; liberated e- are drifted to wire planes where their 2D location can be reconstructed; drift time gives 3rd dimension • For non-beam events, obtaining the drift time relies on detecting the scintillation light (defines t0) • In a LArTPC detector the K+ can be tracked, then it can be possibly ID and its momentum can be measured

Conference on Science at the Sanford Underground Research Facility, SD, 2017 11 Deep Underground Neutrino Experiment

An international mega-science project • CP-violation • Far detector at Sanford Underground • Mass hierarchy Research Facility • Neutrinos from supernova • Proton decay

Conference on Science at the Sanford Underground Research Facility, SD, 2017 12 Deep Underground Neutrino Experiment

• LArTPC technology • detector system • 40-kt of fiducial mass • Being deep (1450m) underground provide an excellent shielding from cosmic rays

• 2015 New collaboration DUNE • 2017 Start excavation at the far site (SURF) • 2018 Two ProtoDUNE Detectors (SP & DP) operational at CERN • 2021 Start of FD installation: 1st module • 2023 Continue FD installation: 2nd module • 2024 20 kt operational • 2026 Beam operations begin at nominal power and proton energy

Conference on Science at the Sanford Underground Research Facility, SD, 2017 13 Deep Underground Neutrino Experiment

• No evidence has been observed so far • Current limits are ~ 1034 years • If you have 1 proton you will need to wait ~ 1034 years and see if it decays!

Massive LArTPC Far Detector • Four 10-kt (fiducial) modules • 1033 !! • Size, location, and technology make this a suitable tool for proton decay search

Conference on Science at the Sanford Underground Research Facility, SD, 2017 14 Proton Decay Signatures at DUNE

Simulation of proton decay at DUNE LArTPC

p→ K+⊽ e+ Collection Plane • GENIE v2.12.0 µ+ • Proton decay from Ar nucleus K+ • Simulation of nuclear effects Fermi motion Induction Plane • ADC • Final state interaction

p→ K+ ⊽ (ticks) Time

K+→ µ+ ⊽µ + + Induction Plane µ → e Ve ⊽µ

Wire number

Conference on Science at the Sanford Underground Research Facility, SD, 2017 15 Proton Decay Signatures at DUNE

Simulation of proton decay at DUNE LArTPC p→ K+⊽

• We have developed an end-to-end e+ Collection Plane simulation and reconstruction chain µ+

• Enabling track reconstruction and PID K+

1400 e+ work in progress Induction Plane 1200 Entries µ+ ADC 1000

800

600 (ticks) Time K+ 400

200

0 Induction Plane 0 5 10 15 20 25 PIDA (dE/dx R0.42)

Wire number

Conference on Science at the Sanford Underground Research Facility, SD, 2017 16 Proton Decay Signatures at DUNE

Simulation of proton decay at DUNE LArTPC p→ K+⊽

1400 1600 e+ work in progress work in progress + Entries 1400 µ

1200 Entries µ+ 1200 1000 1000 800 800 600 K+ 600 400 400 200 200 0 0 5 10 15 20 25 0 0.42 0 50 100 150 200 250 300 350 400 450 500 PIDA (dE/dx R ) Momentum by Range (MeV/c) • The key signature for proton decay search for an isolated charged kaon (kaon ID) • Another quantity that is particularly useful is the ’s momentum from the kaon decay (95% decays-at-rest)

Conference on Science at the Sanford Underground Research Facility, SD, 2017 17 Proton Decay Backgrounds

• Atmospheric neutrinos (vµ CCQE) where a proton is misidentified as kaon • Another potential is cosmogenic-induced kaons, these kaons are produced when cosmic interact with the rock and produce a neutral kaon that enters the detector before undergoing charge exchange

• Most kaons in muon-induced events are accompanied by a non-

work in progress negligible energy deposition quite far from the kaon vertex

Conference on Science at the Sanford Underground Research Facility, SD, 2017 18 Proton Decay Backgrounds

• 39Ar produces light inside the LArTPC which the DUNE FD photon detector system is sensitive to

Ar39

39Ar β decay

• Should this light be reconstructed within the drift window of a cosmogenic background and

confused for t0, the track can seemingly be pulled into the fiducial volume • Monte Carlo simulation of 39Ar activity indicates work in progress setting a threshold of ~10PE on reconstructed light would eliminate the potential background

Conference on Science at the Sanford Underground Research Facility, SD, 2017 19 DUNE Sensitivities

• Given the current reconstruction and analysis tools a preliminary evaluation of signal efficiency and background rate allows to calculate the partial life time sensitivity at 90% C.L for a 400 kton-year exposure

×1033

2 yr)) 40 ⋅ 10 SK current limit 35 /B (years)

30 τ 10 25 20 15 1 10 Background rate (1/(Mton 5 work in progress 10−1 0 10 20 30 40 50 60 70 80 90 100 Signal Efficiency (%)

Conference on Science at the Sanford Underground Research Facility, SD, 2017 20 Summary

• Using LArTPC technology the K+ can be tracked. This is in sharp contrast with water detectors, in which the K+ momentum is below Cherenkov threshold

• DUNE’s massive LArTPC far detector offers a great opportunity to search for proton decay and other number violating processes

• The current status of the automated reconstruction allows to have a preliminary estimation of DUNE’s sensitivity

• DUNE has a rich program from physics to proton decay and more… so stay tuned for exiting news!!

Conference on Science at the Sanford Underground Research Facility, SD, 2017 21 The End

Thanks for listening

DUNE Collaboration, CERN, January 2017

Conference on Science at the Sanford Underground Research Facility, SD, 2017 22 Backups

Conference on Science at the Sanford Underground Research Facility, SD, 2017 23 Challenges of Tracking Kaons

1 1 p → ν K+, hA Model p → ν K+, hN2015 Model K+ before FSI K+ before FSI K+ after FSI K+ after FSI 10−1 K0 10−1 K0 Protons Protons Neutrons

Fraction of Events 10−2 Fraction of Events 10−2

10−3 10−3

10−4 10−4 0 50 100 150 200 250 300 0 50 100 150 200 250 300 Kinetic Energy (MeV) Hadron Kinetic Energy (MeV)

1.2 PMA w/line cluster Final state interaction tends to softer the 1 • PMA w/traj cluster PANDORA 0.8 kaon spectrum

Tracking Efficiency 0.6 • Additional from FSI may 0.4 overlap with kaon tracks 0.2 • The current tracking threshold is ~30 0 0 20 40 60 80 100 120 140 MeV (~15 mm on LAr) Kaon Kinetic Energy (MeV)

Conference on Science at the Sanford Underground Research Facility, SD, 2017 24 Other Decays Modes • Other decay modes where DUNE will have potential of improve on the current limits

see http://pdg.lbl.gov for a full list of potential decay modes

Conference on Science at the Sanford Underground Research Facility, SD, 2017