TrackParamTruthInit: implement relaxed mode to include secondaries in B0TrackerTruthSeeds - #2901
Open
veprbl wants to merge 10 commits into
Open
TrackParamTruthInit: implement relaxed mode to include secondaries in B0TrackerTruthSeeds#2901veprbl wants to merge 10 commits into
veprbl wants to merge 10 commits into
Conversation
… B0TrackerTruthSeeds
for more information, see https://pre-commit.ci
Contributor
There was a problem hiding this comment.
Pull request overview
This PR updates the truth-seeding path for B0 tracking so that displaced secondary tracks (e.g., Λ decay daughters) can be seeded and reconstructed more effectively in the B0 tracker chain by relaxing vertex constraints and allowing the seed’s perigee reference point to be anchored at the production vertex.
Changes:
- Add a dedicated
B0TrackerTruthSeedstruth seeder with relaxed vertex-z acceptance anduseVertexAsPerigee=true. - Introduce
useVertexAsPerigeeinTrackParamTruthInitConfigand expose it via factory parameters. - Propagate the seed’s perigee reference point into CKF initialization (PerigeeSurface center derived from the seed).
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
src/global/tracking/tracking.cc |
Reworks truth-seed factory wiring; adds a dedicated B0 truth seeder with relaxed configuration. |
src/factories/tracking/TrackParamTruthInit_factory.h |
Exposes UseVertexAsPerigee as a configurable parameter. |
src/algorithms/tracking/TrackParamTruthInitConfig.h |
Adds config flag and documentation for vertex-anchored perigee mode. |
src/algorithms/tracking/TrackParamTruthInit.cc |
Implements vertex-anchored perigee option and updates seed perigee storage. |
src/algorithms/tracking/CKFTracking.cc |
Builds the initial perigee surface from the seed’s stored perigee reference point. |
Suppressed comments (1)
src/global/tracking/tracking.cc:63
- "B0TrackerTruthSeeds" now comes from a separate TrackParamTruthInit instance that writes its parameters to "B0TrackerTruthSeedParameters". The default PODIO output collections include "B0TrackerTruthSeeds" but do not include "B0TrackerTruthSeedParameters", which is likely to create dangling relations (TrackSeed -> TrackParameters) in the output file.
app->Add(new JOmniFactoryGeneratorT<TrackParamTruthInit_factory>(
"B0TrackerTruthSeeds", {"EventHeader", "MCParticles"},
{"B0TrackerTruthSeeds", "B0TrackerTruthSeedParameters"},
TrackParamTruthInitConfig{
💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.
… B0TrackerTruthSeeds (fix: iwyu) (#2902) This PR applies the include-what-you-use fixes as suggested by https://github.com/eic/EICrecon/actions/runs/32928057137. Please merge this PR into the branch `pr/relaxed_b0_truth_seeding` to resolve failures in PR #2901. Auto-generated by [create-pull-request][1] [1]: https://github.com/peter-evans/create-pull-request Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Contributor
There was a problem hiding this comment.
Pull request overview
Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.
Suppressed comments (2)
Previously missed (1) — in code that hasn't changed since the last review.
src/algorithms/tracking/TrackParamTruthInit.cc:113
- Potential division-by-zero when computing the transverse PCA if the particle has pT == 0 (p.x == p.y == 0). That will produce NaNs in the seed parameters for exactly-forward tracks. Guard the denominator and fall back to using the vertex as the PCA in this degenerate case.
perigee_center = Acts::Vector3(0, 0, 0);
auto linesurface_parameter = -(v.x * p.x + v.y * p.y) / (p.x * p.x + p.y * p.y);
global = Acts::Vector3(v.x + linesurface_parameter * p.x, v.y + linesurface_parameter * p.y,
v.z + linesurface_parameter * p.z);
src/global/tracking/tracking.cc:50
- This wiring no longer produces a collection named "TrackerTruthSeeds" (it now writes directly to "CentralTrackerTruthSeeds"). However, the PODIO default output list still includes "TrackerTruthSeeds" (see src/services/io/podio/JEventProcessorPODIO.cc:65), so this change can lead to missing/empty collections (and may break user scripts expecting TrackerTruthSeeds). Consider either continuing to produce TrackerTruthSeeds (and optionally aliasing it to CentralTrackerTruthSeeds) or updating the default output collection list accordingly.
app->Add(new JOmniFactoryGeneratorT<TrackParamTruthInit_factory>(
"CentralTrackerTruthSeeds", {"EventHeader", "MCParticles"},
{"CentralTrackerTruthSeeds", "TrackerTruthSeedParameters"}, {}, app));
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Contributor
There was a problem hiding this comment.
Pull request overview
Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.
Suppressed comments (2)
src/global/tracking/tracking.cc:65
maxEtaBackward = 0.0only excludes negative-eta particles; withmaxEtaForward = 6.0this B0 truth seeder will accept all particles with0 <= eta <= 6(including many non-B0-acceptance tracks, e.g. eta≈0), which can dramatically increase the number of truth seeds (and CKF iterations) with no corresponding B0 hits. This also doesn’t match the inline comment “forward-going particles only” if the intent is the sub-50 mrad B0 region. Consider adding an explicit forward lower bound (e.g.minEtaForwardormaxTheta) toTrackParamTruthInitConfig/algorithm, or reinstating an angular split/filter so B0 only seeds the intended small-theta region.
TrackParamTruthInitConfig{
.maxVertexX = 120 * dd4hep::mm, // maxVertexZ * tan(20mrad) ~ 120mm
.maxVertexY = 120 * dd4hep::mm,
.maxVertexZ = 6000 * dd4hep::mm, // B0 tracker starts at ~6 m from IP
.minMomentum = 100 * dd4hep::MeV,
.maxEtaForward = 6.0,
.maxEtaBackward = 0.0, // forward-going particles only
.momentumSmear = 0.1,
.useVertexAsPerigee = true, // anchor at decay vertex, not beam-axis PCA
src/algorithms/tracking/CKFTracking.cc:196
- The initial Acts
PerigeeSurfaceis now constructed attrack_seed.getPerigee(), but later the code still extrapolates every found track to a fixed perigee surface at the IP (Acts::Vector3{0,0,0}) and drops the track if that extrapolation fails. For displaced truth seeds (where the perigee is intentionally moved to the decay vertex), this can still cause secondary tracks to be discarded after successful finding/smoothing, undermining the purpose ofUseVertexAsPerigee. Consider extrapolating to a per-seed reference surface (matching the seed perigee) or accepting the smoothed track even if IP perigee extrapolation fails (e.g. keep it at the seed/measurement reference surface and log a warning).
// Construct the perigee surface at the seed's reference point.
// For IP-originating tracks this is (0,0,0); for displaced seeds (e.g. from
// Lambda decay daughters) the seed carries the actual decay-vertex position
// so the CKF propagates from there instead of from the IP.
const auto& perigee_pos = track_seed.getPerigee();
auto pSurface = Acts::Surface::makeShared<const Acts::PerigeeSurface>(Acts::Vector3(
perigee_pos.x * Acts::UnitConstants::mm, perigee_pos.y * Acts::UnitConstants::mm,
perigee_pos.z * Acts::UnitConstants::mm));
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Contributor
There was a problem hiding this comment.
Pull request overview
Copilot reviewed 6 out of 6 changed files in this pull request and generated no new comments.
Suppressed comments (1)
src/algorithms/tracking/TrackParamTruthInit.cc:113
- Potential division-by-zero in the PCA back-extrapolation when the particle momentum is parallel (or nearly parallel) to the beam axis:
(p.x*p.x + p.y*p.y)can be 0, producing NaNs inlinesurface_parameter/globaland causingglobalToLocalto fail.
// Standard: perigee at beam axis origin, back-extrapolate to transverse PCA.
perigee_center = Acts::Vector3(0, 0, 0);
auto linesurface_parameter = -(v.x * p.x + v.y * p.y) / (p.x * p.x + p.y * p.y);
global = Acts::Vector3(v.x + linesurface_parameter * p.x, v.y + linesurface_parameter * p.y,
v.z + linesurface_parameter * p.z);
Contributor
Capybara summary for PR 2901
Last updated 2026-08-28T15:53-04:00 ca8980f |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Briefly, what does this PR introduce? Please link to any relevant presentations or discussions.
Addresses #2746
What is the urgency of this PR?
What kind of change does this PR introduce?
Please check if any of the following apply
This change removes the legacy TrackerTruthSeeds / TrackerTruthSeedParameters collections from the default PODIO output list and replaces them with the new central/B0-specific names.
B0 tracking works slightly differently, but there should not be a visible change to the user analyses
Claude