Proton Decay p → K+

Aaron Higuera!University of Houston!

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Proton Decay, p → K+ ⌫̄

h_K_PEntries 9389Mean 267.5RMS 104.3

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P

We found a bug in the generation of proton decay events, the seed was not set properly, we generated the same 100 events 10 times and placed at different vertex!!Now is fixed!

unsigned int seed = art::ServiceHandle<sim::LArSeedService>()->getSeed();!genie::utils::app_init::RandGen(seed);

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Proton Decay, p → K+ ⌫̄

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✤ A MIP looses ~2.1 MeV/cm!✤ Kaon are heavy ionization particles!✤ 4 MeV Kaon will travel ~2 cm 2-3 wires!✤ Kaons below 25 MeV of KE are stubs

hard to track them!✤ Why so many Kaons with low KE?!

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K+ and GENIE 2.10.10✤ Proton decay model dependence? !✤ Nuclear mode!

RFG with short range nucleon-nucleon correlations! No biding energy! No de-excitation photon production for Ar, only for Oxygen

(Cherenkov detectors)!

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K+ and GENIE 2.10.10✤ Kaon-nucleus !

✤ K+ absorption is forbidden!✤ K+ can charge exchange into K0!✤ π+n can produce K by strong process!

!✤ Kaon-nucleus & GENIE FSI!

FSI are simulated using “hA” model! No absorption! Elastic and Inelastic scattering! K+ via π is not included! No K+ charge exchange! GENIE FSI model never adds or

removes K+ from the final state!!

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Kaon after FSI!Kaon at vtx

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K+ and GENIE 2.10.10!✤ Kaon-nucleus & GENIE FSI!

FSI are simulated using “hA” model! No absorption! Elastic and Inelastic scattering! K+ via π is not included! No K+ charge exchange! GENIE FSI model never adds or

removes K+ from the final state!! Kaon Momentum (MeV)

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Kaon after FSI!Kaon at vtx

Kaon after FSI!Kaon at vtx

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Kaon Inelastic scattering!47.2%!

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K+ and LAr!✤ Kaon-nucleus

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Kaon after FSI!Kaon at vtx

D. Stefan, Artur M. Ankowski!Acta Physica Polonica B Vol. 40 (2009)

✤ Fluka & GEANT4 simulation!✤ Fermi vs Spectral Functions!✤ Bertini cascade model w &w/o!✤ 2.0 % of K are lost due charge exchange!✤ Overall the result is similar to GENIE

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Kaon Momentum (MeV)0 50 100 150 200 250 300 350 400 450 5000

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Kaon after FSI!Kaon at vtx

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Kaon after FSI!Kaon at vtx

✤ On Oxygen✤ On Argon

Proton Decay, p → K+ ⌫̄

✤ FSI modifies kaon momentum !✤ GENIE 2.11.2 to include K+FSI in hN (better developed than hA)!

More nucleon decays modes!

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Reconstruction: LineCluster vs TrajCluster

TrajCluster gives ~4% increase in tracking eff for kaons and muons and ~9% for electrons

To ID kaons and muons we rely track reconstruction

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h_PID_kEntries 3892Mean 13.21RMS 3.536

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h_PID_kEntries 4103Mean 11.39RMS 5.252

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h_PID_muEntries 6836Mean 7.74RMS 3.656

h_PID_muEntries 6836Mean 7.74RMS 3.656

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h_PID_kEntries 3892Mean 13.21RMS 3.536

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h_PID_kEntries 3892Mean 13.21RMS 3.536

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h_PID_kEntries 4103Mean 11.39RMS 5.252

h_PID_kEntries 4103Mean 11.39RMS 5.252

LineCluster!TrajCluster

Reconstruction: LineCluster vs TrajCluster

TrajCluster

LineCluster!

LineCluster!

TrajCluster

We have identify some issues with trajcluster: Break clusters when there is a change in charge… working on !For now we will use lineCluster until trajcluster produces equally good or better results

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Proton Decay, p → K+ ⌫̄

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Kaon!Muon+!Michel e+!Proton!Others

Signal Efficiency

Kaon ID 53.3%

Stopping Muon 37.1%

210<p<250 MeV 26.7%

1) A Kaon ID!2) A stopping muon with 210< pµ < 250 MeV!

So far event selection relies on track reconstruction and PIDA!PIDA depends on track reconstruction (decay point)

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Proton Decay, p → K+ ⌫̄

1) A stopping track with momentum 210< pµ < 250 MeV!

pµ =m2

k�m2µ

2mk= 239 MeV

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Muon+!95% of the Kaons (muon decay) decay at rest

Muon tracking efficiency is ~90%!Momentum by range is less sensitive to missID of the decay point

Signal Efficiency

Stoping track 210<p<250 MeV 78%

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Proton Decay, p → K+ ⌫̄

1) A stopping track with momentum 210< pµ < 250 MeV!

!2) Kaon candidate{ Pass Kaon PIDA criterion (golden events)

Look for heavy ionization hits in or by the muon track

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Trying to improve here

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Missing Kaon Track

Look for heavy ionization hits in or by the muon track

K = 65 MeV (KE) P = 36 MeV (KE) n = 55 MeVK

µp

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Missing Kaon Track

Look for heavy ionization hits in or by the muon track

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Inte

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Muon Track CleaningRough idea: remove heavy ionization hits at the beginning/end of a track, re-run track reconstruction (doesn’t look straightforward … need a lot of work within LArSoft)!Potential issue: proton and kaon hits are pretty similar (charge)

Wire ID

{

Heavy ionization hits

Delta ray

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Missing Kaon Track

Look for heavy ionization hits

K = 15 MeV (KE) P = 65 MeV (KE)

pK

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Comments✤ There are a lot of challenges ahead!

✤ Kaon FSI introduces extra pain!✤ Move towards a event selection based on the muon!✤ Improve muon reconstruction (track cleaning, CNN vertices)!✤ Maybe we can improve event selection efficiency up to ~75%!

List of possible NDK modes where DUNE may have an early discovery potential (docdb 1644)

We should think twice when we promise something especially if include kaons!