DUNE Searches For Baryon Number ... - Department of Physics

DUNE Searches For Baryon Number Violation

Aaron HigueraUniversity of Houston

On behalf of the DUNE Collaboration

Conference on Science at the Sanford Underground Research Facility, SD, 2019

Outlook


• Introduction

• DUNE Experiment

• Nucleon Decay Signatures at DUNE

• Neutron Oscillation Signatures at DUNE

• Summary

Introduction


• Baryon Number is a symmetry of nature

• The stability of ordinary matter is attributed to the conservation of B

• Formulated by Weyl 1929, Stueckelberg (1938),

Wigner (1949), Lee & Yang (1950)

Proton Neutron

A conservation law for heavy particles is responsible for the stability of protons in the same way as the conservation law for charges is responsible for the stability of the electron

However the stability of proton is not guaranteed by an analogous “fundamental” symmetry

Electron

3

Introduction


• Baryon Number is a symmetry of Nature

• The stability of ordinary matter is attribute to the conservation of B

• Formulated by Weyl 1929, Stueckelberg (1938),

Wigner (1949), Lee & Yang (1950)

Proton Neutron

If baryon number is only an approximate symmetry which is broken by small amounts, as many leading theoretical ideas suggest, it would have a profound impact on our understanding of the Universe

Electron

4


5

Grand Unified Theories (GUTs)

A natural coincidence of GUTs is Baryon Number Violation (BNV)Nucleon decay process (ΔB =1)

New physics below GUT scale Neutron — anti-neutron oscillation (ΔB =2)

Wea

knes

s of

forc

e

Wea

knes

s of

forc

e

Energy (GeV)Energy (GeV)

Standard Model GUT (Unified Force)

~1016 GeVelectromagnetic

weak

strong


6

Experimental Scenario for BNV Searches

Nucleon decay process Searches via large mass detectors with low background (underground)

Neutron — anti-neutron oscillation Searches via large mass detector (bound neutron) and accelerator (quasi-free conditions)


7


Nucleon decay current status

Ed Kearns BLV 2017


8


Neutron — anti-neutron oscillation

Current best limits on free neutron lifetime:

Super-K oxygen-bound neutron search: τ > 2.7 x108 s (90%CL) [arXiv:1109.4227]

SNO deuterium-bound neutron search: τ > 1.23 x108 s (90%CL) [arXiv:1705.00696]


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Deep Underground Neutrino Experiment

An international mega-science project• CP-violation • Mass hierarchy• Neutrinos from supernova • Nucleon decay & n-nbar oscillation

• Far detector at Sanford Underground Research Facility


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• LArTPC technology • Photon detector system• 40-kt of fiducial mass• Being deep (1450m)

underground provide an excellent shielding from cosmic rays

• 2015 New collaboration DUNE • 2017 Excavation at the far site (SURF)• 2018 ProtoDUNE Detector (SP) data taking at CERN & analysis underway • 2019 ProtoDUNE Detector (DP) data taking at CERN• 2018 TDR completed for both single and dual phase• 2024 Start of FD installation: 1st module • 2026 Beam operations begin at nominal power and proton energy

• 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)


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• ~3.3 x 1032 p ~2.7 x 1032 n per k-ton• Four 10-kt (fiducial) modules• LArTPC technology exhibits a

significant performance advantage

Massive LArTPC Far Detector


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Nucleon Decay Signatures at DUNE

• GENIE v2.12.10 • Proton decay from Ar nucleus • Simulation of nuclear effects

• Fermi motion• Final state interaction

Simulation of proton decay at DUNECollection Plane

Induction Plane

Induction PlaneTime

(ticks

)

Wire number

K+

µ+e+p ! K+⌫̄

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p ! K+⌫̄<latexit sha1_base64="ak0xMkiVn49XyQXTreY9fmKj5ec=">AAACCXicbVDLSsNAFJ3UV62vqEs3g40gCCWpC10W3QhuKtgHNLFMptN26GQmzEyUErJ146+4caGIW//AnX/jtM1CWw9cOJxzL/feE8aMKu2631ZhaXllda24XtrY3NresXf3mkokEpMGFkzIdogUYZSThqaakXYsCYpCRlrh6HLit+6JVFTwWz2OSRChAad9ipE2UteGjhP7kg6GGkkpHuD1XXqSQT9EMvV5kjlO1y67FXcKuEi8nJRBjnrX/vJ7AicR4RozpFTHc2MdpEhqihnJSn6iSIzwCA1Ix1COIqKCdPpJBo+M0oN9IU1xDafq74kURUqNo9B0RkgP1bw3Ef/zOonunwcp5XGiCcezRf2EQS3gJBbYo5JgzcaGICypuRXiIZIIaxNeyYTgzb+8SJrVindaqd5Uy7WLPI4iOACH4Bh44AzUwBWogwbA4BE8g1fwZj1ZL9a79TFrLVj5zD74A+vzBzzCmWY=</latexit>

K+ ! µ+⌫̄µ<latexit sha1_base64="m0n4zr6NenvZj9L4vSYvFRYSdgU=">AAACFnicbZDLSsNAFIYnXmu9RV26GWwEQSxJXeiy6EZwU8FeoIlhMp22QyeTMDNRSshTuPFV3LhQxK24822ctFlo6w8DP985hzPnD2JGpbLtb2NhcWl5ZbW0Vl7f2NzaNnd2WzJKBCZNHLFIdAIkCaOcNBVVjHRiQVAYMNIORpd5vX1PhKQRv1XjmHghGnDapxgpjXzzxLKu79LjzBV0MFRIiOgBQjdMcgbdAInU5UnmpxplluWbFbtqTwTnjVOYCijU8M0vtxfhJCRcYYak7Dp2rLwUCUUxI1nZTSSJER6hAelqy1FIpJdOzsrgoSY92I+EflzBCf09kaJQynEY6M4QqaGcreXwv1o3Uf1zL6U8ThTheLqonzCoIphnBHtUEKzYWBuEBdV/hXiIBMJKJ1nWITizJ8+bVq3qnFZrN7VK/aKIowT2wQE4Ag44A3VwBRqgCTB4BM/gFbwZT8aL8W58TFsXjGJmD/yR8fkDbJie7A==</latexit>

µ+ ! e+⌫e⌫̄µ<latexit sha1_base64="r27/4rcbpWMDK/i0gx057iQscTU=">AAACH3icbVDLSgMxFM3UV62vqks3wVYQhDJTQV0W3bisYB/QGYdMetuGZjJDklHKMH/ixl9x40IRcde/MX0stPVAyMm553JzTxBzprRtj63cyura+kZ+s7C1vbO7V9w/aKookRQaNOKRbAdEAWcCGpppDu1YAgkDDq1geDOptx5BKhaJez2KwQtJX7Aeo0QbyS9elMtumDykZxl2JesPNJEyesIYZpJI/BTMHRCZmkfmp8adlct+sWRX7CnwMnHmpITmqPvFb7cb0SQEoSknSnUcO9ZeSqRmlENWcBMFMaFD0oeOoYKEoLx0ul+GT4zSxb1ImiM0nqq/O1ISKjUKA+MMiR6oxdpE/K/WSXTvykuZiBMNgs4G9RKOdYQnYeEuk0A1HxlCqGTmr5gOiCRUm0gLJgRnceVl0qxWnPNK9a5aql3P48ijI3SMTpGDLlEN3aI6aiCKntErekcf1ov1Zn1aXzNrzpr3HKI/sMY/aLeimw==</latexit>


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Collection Plane

Induction Plane

Induction PlaneTi

me

(ticks

)

Wire number

K+

µ+e+

0 5 10 15 20 25 PIDA

Arbi

trary

Uni

ts

MuonKaon

Proton

Event Selection

• LArTPC sensitive to FSI• Particle ID via dE/dx

• Particle momentum (range or calorimetry)

PIDA =P

i

dE

dxiR0.42

i

<latexit sha1_base64="y7f8ff5SrckG7hKRgbmIN75SHQw=">AAACHHicbVDLSsNAFJ34rPUVdelmsBVchbQVdCPUF+iuin1AE8tkMmmHTh7MTMQS8iFu/BU3LhRx40Lwb5y0RbT1wOUezrmXmXuciFEhTfNLm5mdm19YzC3ll1dW19b1jc2GCGOOSR2HLOQtBwnCaEDqkkpGWhEnyHcYaTr908xv3hEuaBjcyEFEbB91A+pRjKSSOnqlWLs8O4ZH0BKx30loCi2PI5y452ni3mdCCq+zdpuYxn45LVpWvqMXTMMcAv6Q0iQpgDFqHf3DckMc+ySQmCEh2iUzknaCuKSYkTRvxYJECPdRl7QVDZBPhJ0Mj0vhrlJc6IVcVSDhUP29kSBfiIHvqEkfyZ6Y9DLxP68dS+/QTmgQxZIEePSQFzMoQ5glBV3KCZZsoAjCnKq/QtxDKhyp8sxCmDp5mjTKRqlilK/KherJOI4c2AY7YA+UwAGoggtQA3WAwQN4Ai/gVXvUnrU37X00OqONd7bAH2if33RMoFs=</latexit>


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Image Classification (Convolutional neural network CNN)

signal p→ K+ ⊽

bkgd atm neutrino interaction

CNN inputs are mapped to feature maps after every convolution layer

The weight of these mappings are learned through training, by being updated over iterations

At every iteration, loss function is evaluated, and the loss is attempted to be minimized over iterations


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Image Classification (Convolutional neural network CNN)

signal p→ K+ ⊽

bkgd atm neutrino interaction


16


Multi-variable Analysis (Boosted Decision Tree)

0 5 10 15 20 25 PIDA

Arbi

trary

Uni

ts

MuonKaon

Proton

+ +

+ … Event Classification=


17Neutron— Anti-neutron Oscillation Signatures at DUNE

• GENIE v2.12.10

• In nuclei, bound neutron’s oscillation to an anti-neutron is followed by the annihilation with nearby nucleon.

• Oscillated anti-neutron has 21/39 chance of annihilation with neutron, 18/39 chance with proton in 40Ar

Collection Plane

Induction Plane

Induction PlaneTime

(ticks

)

Wire number

π-

π+

π0

π0


18Neutron— Anti-neutron Oscillation Signatures at DUNE

signal

Image Classification Standard reconstruction

track & vertex multiplicityPID visible energy …

Multi-variable Analysis (Boosted Decision Tree)


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Summary• Using LArTPC technology offers great advantages in terms of event

reconstruction

• DUNE’s massive LArTPC far detector offers a great opportunity to search for baryon number violating processes

• The current status of the automated reconstruction allows to have a preliminary estimation of DUNE’s sensitivity that is competitive with current and future experiments, results will be public on the technical design report this year (TDR)

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


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The End

Thanks for listening


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Backups


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Final State Interactions

0 50 100 150 200 250 300Kaon Kinetic Energy (MeV)

0

100

200

300

400

500

600

700

800

Even

ts

primaryfinal state

0 50 100 150 200 250 300Nucleon Kinetic Energy (MeV)

0

100

200

300

400

500

600

700protonneutron

• Final state interaction tends to softer the kaon spectrum• Additional nucleons from FSI may overlap with kaon tracks• The current tracking threshold is ~30 MeV (~15 mm on LAr)


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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 muons 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-negligible energy deposition quite far from the kaon vertex

work in progress

39Ar β decay


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Proton Decay Backgrounds

work in progress

Ar39

• Should this light be reconstructed within the drift window of a cosmogenic background and confused t0, the track can seemingly be pulled into the fiducial volume • Monte Carlo simulation of 39Ar activity indicates

setting a threshold of ~10PE on reconstructed light would eliminate the potential background

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


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Neutron — Anti-neutron oscillation

The bound neutron lifetime to free neutron lifetime are related through the nuclear potential suppression factor R, which depends on the nucleus

For argon, the suppression factor of 56Fe, R = 0.666e23 s-1, could be suitable to use with the extra theoretical uncertainty applied

⌧2n�n̄ =Tn�n̄

R<latexit sha1_base64="YuSy/VbsTxfAQ5orMgMv4k5zjv4=">AAACGnicbVC7TsMwFHXKq5RXgZHFokVioUrKAAtSBQtjQX1JTagc12mtOk5kO0iVle9g4VdYGECIDbHwN7hthtJypCsdnXOv7r3HjxmVyrZ/rNzK6tr6Rn6zsLW9s7tX3D9oySgRmDRxxCLR8ZEkjHLSVFQx0okFQaHPSNsf3Uz89iMRkka8ocYx8UI04DSgGCkj9YpOuewqlDzoatrT/Mz1kdA8Ta/cQCCsG/MaTPV9Wi73iiW7Yk8Bl4mTkRLIUO8Vv9x+hJOQcIUZkrLr2LHyNBKKYkbSgptIEiM8QgPSNZSjkEhPT19L4YlR+jCIhCmu4FSdn9AolHIc+qYzRGooF72J+J/XTVRw6WnK40QRjmeLgoRBFcFJTrBPBcGKjQ1BWFBzK8RDZEJRJs2CCcFZfHmZtKoV57xSvauWatdZHHlwBI7BKXDABaiBW1AHTYDBE3gBb+DderZerQ/rc9aas7KZQ/AH1vcvXeKhEg==</latexit>


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CNN

• Input: 4887 time-ticks (1 drift time) and 960 collection plane recob::wire objects (1 APA) are down-sampled by the factor of 8 (time-tick axis), factor of 2 (wire axis), and placed on a 600x600 pixel frame state interaction tends to softer the kaon spectrum

• 16 layers using Caffe framework

DUNE Searches For Baryon Number ... - Department of Physics

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