HNL 2-body decays by austinschneider · Pull Request #109 · Harvard-Neutrino/SIREN

austinschneider · 2026-04-28T04:29:08Z

Stack: PR 11 of 14

This PR is part of a 14-PR stack decomposing dev/HNL_DIS into reviewable chunks.

Base: feat/hnl-dis-from-spline
Head: feat/hnl-decays-2body

Merge order: feat/hnl-dis-from-spline should land before this PR.

Squashed contents

Squashed diff for paths:

projects/dataclasses/private/InteractionRecord.cxx
projects/dataclasses/public/SIREN/dataclasses/InteractionRecord.h
projects/dataclasses/public/SIREN/dataclasses/ParticleMasses.h
projects/dataclasses/public/SIREN/dataclasses/ParticleTypes.def
projects/utilities/public/SIREN/utilities/Constants.h

Source commits on dev/HNL_DIS_clean that contributed:
21451da (Nicholas Kamp): first attempt at external list primary injector
3625e81 (Nicholas Kamp): fix build errors, add 3 nu decay
5031575 (Nicholas Kamp): initial suite of changes to re-implement the dipole DIS from spline class in the SIREN parlance
ac0ce24 (Nicholas Kamp): changes to facilitate hadronic and W/Z HNL decays
dc0281b (Nicholas Kamp): Total decay widths implemented, add ND280 detector
ea13b30 (nickkamp1): Rename some classes, flush out the two body decay class
f6f8b46 (Nicholas Kamp): get the decay sampling working

Notes

This branch is the squashed cumulative diff of the listed source commits. Per-commit history is browsable on dev/HNL_DIS_clean.
Large .fits data files have been removed from the branch and are packaged separately.

Copilot

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds particle/constant definitions needed to support HNL 2-body decay modeling and propagates per-interaction parameters into the finalized interaction record.

Changes:

Expanded particle constants (meson/quark masses, weak/CKM parameters).
Extended particle type enum definitions (quarks, HNL antiparticles, additional mesons/B hadrons).
Introduced a particle-mass lookup table and added plumbing for interaction_parameters into InteractionRecord finalization.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
projects/utilities/public/SIREN/utilities/Constants.h	Adds hadron/quark masses and weak/CKM constants for decay calculations.
projects/dataclasses/public/SIREN/dataclasses/ParticleTypes.def	Extends `ParticleType` list with quarks, new hadrons, and HNL antiparticles.
projects/dataclasses/public/SIREN/dataclasses/ParticleMasses.h	Introduces a central mapping from `ParticleType` to mass and a lookup function.
projects/dataclasses/public/SIREN/dataclasses/InteractionRecord.h	Adds `interaction_parameters` storage and setters to the primary distribution record.
projects/dataclasses/private/InteractionRecord.cxx	Copies `interaction_parameters` into the finalized `InteractionRecord`.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot · 2026-04-28T04:36:04Z

+X(KPrime0, 9000311)
+X(KPrimePlus, 9000321)
+X(KPrimeMinus, -9000321)


These PDG IDs look inconsistent with the masses introduced for KPrime* (≈0.892–0.896 GeV), which match the standard K*(892) resonances. Standard PDG IDs for K*(892) are typically 313 (K0), 323 (K+), and -323 (K*-). If downstream code relies on PDG IDs for serialization, lookups, or physics logic, this mismatch will cause incorrect behavior. Consider switching to the standard IDs (or documenting/enforcing a project-specific PDG extension scheme consistently across all particles).

Suggested change

X(KPrime0, 9000311)

X(KPrimePlus, 9000321)

X(KPrimeMinus, -9000321)

X(KPrime0, 313)

X(KPrimePlus, 323)

X(KPrimeMinus, -323)

Copilot · 2026-04-28T04:36:05Z

+    {ParticleType::PPlus,      siren::utilities::Constants::protonMass},
+    {ParticleType::PMinus,     siren::utilities::Constants::protonMass},
+    {ParticleType::Neutron,    siren::utilities::Constants::neutronMass},
+    {ParticleType::EMinus,     siren::utilities::Constants::electronMass},


ParticleType::EPlus exists (and is commonly produced in decays), but it is not mapped here. Any call to GetParticleMass(ParticleType::EPlus) will silently return 0.0, which will break kinematics. Add EPlus mapped to electronMass (and consider similarly adding obvious missing entries that are already defined in ParticleTypes.def, e.g. B0 if it’s intended to be used).

Suggested change

{ParticleType::EMinus, siren::utilities::Constants::electronMass},

{ParticleType::EMinus, siren::utilities::Constants::electronMass},

{ParticleType::EPlus, siren::utilities::Constants::electronMass},

Copilot · 2026-04-28T04:36:05Z

+inline double GetParticleMass(ParticleType type) {
+    auto it = ParticleMasses.find(type);
+    if (it != ParticleMasses.end())
+        return it->second;
+    return 0.0; // or throw, or std::numeric_limits<double>::quiet_NaN()
+}


Returning 0.0 for an unknown/unmapped particle type makes failures hard to detect and can silently corrupt physics (many valid particles are also effectively massless in this context). Prefer a behavior that is distinguishable from valid results (e.g., throw, assert, or return quiet_NaN()), and document the contract for callers.

Copilot · 2026-04-28T04:36:05Z

+    //record.interaction_parameters = interaction_parameters;
+    for (auto x : interaction_parameters) {
+        record.interaction_parameters[x.first] = x.second;
+    }


The commented-out assignment changes semantics: the loop only overwrites/sets keys that exist in interaction_parameters, but it does not remove keys already present in record.interaction_parameters. If record can be reused or previously populated, this can leave stale parameters behind. If the intent is to fully replace, use direct assignment (or clear the destination before the loop).

Suggested change

//record.interaction_parameters = interaction_parameters;

for (auto x : interaction_parameters) {

record.interaction_parameters[x.first] = x.second;

}

record.interaction_parameters = interaction_parameters;

Copilot · 2026-04-28T04:36:05Z

    record.primary_mass = GetMass();
    record.primary_momentum = GetFourMomentum();
    record.primary_helicity = GetHelicity();
+    for (auto x : interaction_parameters) {


for (auto x : interaction_parameters) copies each map element (including the string key). Use const auto& to avoid per-entry copying when transferring parameters.

Suggested change

for (auto x : interaction_parameters) {

for (const auto& x : interaction_parameters) {

Copilot · 2026-04-28T04:36:06Z

+// Quark masses from https://pdg.lbl.gov/2020/reviews/rpp2020-rev-quark-masses.pdf
+static const double upMass          = 0.00232; // GeV
+static const double downMass        = 0.00471; // GeV
+static const double charmMass       = 1.280; // GeV
+static const double strangeMass     = 0.0929; // GeV
+static const double topMass         = 173.3; // GeV
+static const double bottomMass      = 4.198; // GeV


Quark masses are scheme/scale dependent (e.g., MS-bar at a reference scale vs pole mass), and PDG typically reports ranges/definitions rather than a single universal value. To prevent misuse, please document the intended scheme/scale/definition for these constants (and whether they’re only meant for approximate kinematics), especially if they feed into decay widths/branching calculations.

Suggested change

// Quark masses from https://pdg.lbl.gov/2020/reviews/rpp2020-rev-quark-masses.pdf

static const double upMass = 0.00232; // GeV

static const double downMass = 0.00471; // GeV

static const double charmMass = 1.280; // GeV

static const double strangeMass = 0.0929; // GeV

static const double topMass = 173.3; // GeV

static const double bottomMass = 4.198; // GeV

// Quark masses are scheme/scale dependent and are documented here to avoid

// treating them as universal "rest masses" in all calculations.

// Source: PDG 2020 quark-mass review

// https://pdg.lbl.gov/2020/reviews/rpp2020-rev-quark-masses.pdf

//

// Intended definitions used in this header:

// * upMass, downMass, strangeMass: MS-bar running masses at mu = 2 GeV

// * charmMass: MS-bar running mass m_c(m_c)

// * bottomMass: MS-bar running mass m_b(m_b)

// * topMass: top-quark pole-mass-style value

//

// These constants should therefore be used only for approximate kinematics,

// thresholds, or places where the specific convention above is acceptable.

// Do not reuse them in decay-width / branching-ratio / precision matrix-element

// calculations without verifying the required renormalization scheme and scale.

static const double upMass = 0.00232; // GeV, MS-bar at 2 GeV

static const double downMass = 0.00471; // GeV, MS-bar at 2 GeV

static const double charmMass = 1.280; // GeV, MS-bar m_c(m_c)

static const double strangeMass = 0.0929; // GeV, MS-bar at 2 GeV

static const double topMass = 173.3; // GeV, pole-mass-style value

static const double bottomMass = 4.198; // GeV, MS-bar m_b(m_b)

austinschneider · 2026-04-28T13:08:33Z

Closing — after fixing build dependencies, the branch's contributions (InteractionRecord, ParticleTypes.def, ParticleMasses.h, Constants.h) had to land earlier in the stack so that feat/primary-external-distribution and feat/hnl-dis-from-spline build standalone. Those changes are now in #104 (PrimaryExternal) and #108 (HNL DIS) respectively, leaving this PR empty.

#110 (HNL hadronic/EW decays) has been retargeted to base off #108 directly.

Copilot AI review requested due to automatic review settings April 28, 2026 04:29

austinschneider force-pushed the feat/hnl-dis-from-spline branch from 2594915 to 7c3628d Compare April 28, 2026 04:34

austinschneider force-pushed the feat/hnl-decays-2body branch from 9730149 to 6308e14 Compare April 28, 2026 04:34

Copilot AI reviewed Apr 28, 2026

View reviewed changes

austinschneider force-pushed the feat/hnl-dis-from-spline branch from 7c3628d to 497a4bf Compare April 28, 2026 05:09

austinschneider force-pushed the feat/hnl-decays-2body branch from 6308e14 to cb29e52 Compare April 28, 2026 05:09

austinschneider force-pushed the feat/hnl-dis-from-spline branch from 497a4bf to dffa635 Compare April 28, 2026 06:04

austinschneider closed this Apr 28, 2026

austinschneider force-pushed the feat/hnl-decays-2body branch from cb29e52 to dffa635 Compare April 28, 2026 06:04

austinschneider deleted the feat/hnl-decays-2body branch April 28, 2026 13:08

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

HNL 2-body decays#109

HNL 2-body decays#109
austinschneider wants to merge 0 commit into
feat/hnl-dis-from-splinefrom
feat/hnl-decays-2body

austinschneider commented Apr 28, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

Copilot AI Apr 28, 2026

Uh oh!

Copilot AI Apr 28, 2026

Uh oh!

Copilot AI Apr 28, 2026

Uh oh!

Copilot AI Apr 28, 2026

Uh oh!

Copilot AI Apr 28, 2026

Uh oh!

Copilot AI Apr 28, 2026

Uh oh!

austinschneider commented Apr 28, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

	{ParticleType::EMinus, siren::utilities::Constants::electronMass},
	{ParticleType::EMinus, siren::utilities::Constants::electronMass},
	{ParticleType::EPlus, siren::utilities::Constants::electronMass},

	for (auto x : interaction_parameters) {
	for (const auto& x : interaction_parameters) {

-// Quark masses from https://pdg.lbl.gov/2020/reviews/rpp2020-rev-quark-masses.pdf
-static const double upMass          = 0.00232; // GeV
-static const double downMass        = 0.00471; // GeV
-static const double charmMass       = 1.280; // GeV
-static const double strangeMass     = 0.0929; // GeV
-static const double topMass         = 173.3; // GeV
-static const double bottomMass      = 4.198; // GeV
+// Quark masses are scheme/scale dependent and are documented here to avoid
+// treating them as universal "rest masses" in all calculations.
+// Source: PDG 2020 quark-mass review
+// https://pdg.lbl.gov/2020/reviews/rpp2020-rev-quark-masses.pdf
+//
+// Intended definitions used in this header:
+//   * upMass, downMass, strangeMass: MS-bar running masses at mu = 2 GeV
+//   * charmMass: MS-bar running mass m_c(m_c)
+//   * bottomMass: MS-bar running mass m_b(m_b)
+//   * topMass: top-quark pole-mass-style value
+//
+// These constants should therefore be used only for approximate kinematics,
+// thresholds, or places where the specific convention above is acceptable.
+// Do not reuse them in decay-width / branching-ratio / precision matrix-element
+// calculations without verifying the required renormalization scheme and scale.
+static const double upMass          = 0.00232; // GeV, MS-bar at 2 GeV
+static const double downMass        = 0.00471; // GeV, MS-bar at 2 GeV
+static const double charmMass       = 1.280; // GeV, MS-bar m_c(m_c)
+static const double strangeMass     = 0.0929; // GeV, MS-bar at 2 GeV
+static const double topMass         = 173.3; // GeV, pole-mass-style value
+static const double bottomMass      = 4.198; // GeV, MS-bar m_b(m_b)

Uh oh!

Conversation

austinschneider commented Apr 28, 2026

Stack: PR 11 of 14

Squashed contents

Notes

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Copilot AI Apr 28, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Apr 28, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Apr 28, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Apr 28, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Apr 28, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Apr 28, 2026

Choose a reason for hiding this comment

Uh oh!

austinschneider commented Apr 28, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants