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Adds 4 files to the MeVPrtl generator. 2 files are the new tools required to create and decay LLPs, and the other 2 files are the relevant CMakeLists. The Kaon2LLPFlux_tool.cc is in the process of validation and is being pushed so that other collaborators can work on it. The LLPMakeDecay_tool.cc is not complete, but is pushed to allow the rest of the workflow to operate properly.

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  • Does this PR require merging another PR in a different repository (such as sbnanobj/sbnobj etc.)? If so, please link it in the description. -> in sbndcode it requires "MeVPrtl LLP (fcls and files)"
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@SabrinaBrickner SabrinaBrickner added the enhancement New feature or request label Oct 7, 2025
* @brief Kaon2LLPFlux class definiton
*
* Implementation of Kaon->LLP branching ratio taken from:
* arXiv:1912.07622
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What equation do you use from arXiv:1912.07622?


// Branch the parent Kaon Decay
double llp_mass = fM;
double br = 1;
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This should be configurable with a fcl parameter in case we want to add multiple decay modes: K --> mu + LLP, K --> e + LLP...

// Branch the parent Kaon Decay
double llp_mass = fM;
double br = 1;
bool is_muon = true;
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This should be configurable with a fcl parameter, and add the support in case it is a pion instead.

llp.mass = fM;

llp.meson_pdg = kaon.meson_pdg;
llp.secondary_pdg = (is_muon ? 13 : 11) * (kaon.meson_pdg > 0 ? 1 : -1);
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Add support for pion case


llp.meson_pdg = kaon.meson_pdg;
llp.secondary_pdg = (is_muon ? 13 : 11) * (kaon.meson_pdg > 0 ? 1 : -1);
llp.generator = 1; // kLLP
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This code corresponds to the HNL. Add a new one to sbnobj/Common/EventGen/MeVPrtl/MeVPrtlTruth.h

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I did not review this module.

@jicrespo
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For the record, this is an ongoing review and it is not required to converge for the SBND Fall Production.

@kjplows
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kjplows commented Dec 14, 2025

Hi folks! Just a quick Q -- is the status of this PR still work-in-progress?
If yes, I suggest you update your branch occasionally @SabrinaBrickner -- that way you minimise the chance of merge commits doing funny things to your code 😅
Thanks!

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5 participants