perf: use analytical solution for straight tracks during impact point estimation

[felix-russo]

We use the Newton method to find the 3D PCA for helical tracks. Straight tracks are currently approximated by setting the helix radius to a very large value.

In this PR, the approximation is replaced by an analytical solution (which exists for straight tracks). This should lead to a better performance and (slightly) more precise results. To check the analytical solution, a unit test is added.

A derivation of the analytical solution can be found in the updated reference: Track_Linearization_and_3D_PCA.pdf

[codecov]

Codecov Report

Merging #2506 (799b25b) into main (020a076) will decrease coverage by 0.01%.
The diff coverage is 30.43%.

@@            Coverage Diff             @@
##             main    #2506      +/-   ##
==========================================
- Coverage   49.77%   49.77%   -0.01%     
==========================================
  Files         466      466              
  Lines       26298    26310      +12     
  Branches    12084    12093       +9     
==========================================
+ Hits        13091    13095       +4     
+ Misses       4617     4616       -1     
- Partials     8590     8599       +9     

Files	Coverage Δ
...re/include/Acts/Vertexing/ImpactPointEstimator.hpp	100.00% <ø> (ø)
...re/include/Acts/Vertexing/ImpactPointEstimator.ipp	36.89% <30.43%> (-0.23%)	⬇️

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[github-actions]

📊: Physics performance monitoring for 799b25b

Full contents

physmon summary

• ✅ CKF truth_smeared
• ✅ IVF truth_smeared
• ✅ AMVF truth_smeared
• ✅ Track Summary CKF truth_smeared
• ✅ Seeding truth_estimated
• ✅ CKF truth_estimated
• ✅ IVF truth_estimated
• ✅ AMVF truth_estimated
• ✅ Track Summary CKF truth_estimated
• ✅ Seeding seeded
• ✅ CKF seeded
• ✅ IVF seeded
• ✅ AMVF seeded
• ✅ AMVF (+grid seeder) seeded
• ✅ Track Summary CKF seeded
• ✅ Seeding orthogonal
• ✅ CKF orthogonal
• ✅ IVF orthogonal
• ✅ AMVF orthogonal
• ✅ Track Summary CKF orthogonal
• ✅ Ambisolver seeded
• ✅ Ambisolver orthogonal
• ✅ Seeding ttbar
• ✅ CKF ttbar
• ✅ Ambisolver
• ✅ Track Summary CKF ttbar
• ✅ AMVF ttbar
• ✅ AMVF (+grid seeder) ttbar
• ✅ Truth tracking (GSF)
• ✅ Truth tracking
• ✅ Particles inital fatras
• ✅ Particles final fatras
• ✅ Particles inital geant4
• ✅ Particles final geant4

[acts-project-service]

🔴 Athena integration test results

🔴 Some tests have failed!

Please investigate the pipeline!

status	job
🟢	run_unit_tests
🟢	run_ci_tests: ../athena/AtlasTest/CITest/test/ActsWorkflow.sh
🟢	run_ci_tests: ../athena/AtlasTest/CITest/test/ActsValidateTracks.sh
🟢	run_ci_tests: ../athena/AtlasTest/CITest/test/ActsValidateActsCoreSpacePoints.sh
🟢	run_ci_tests: ../athena/AtlasTest/CITest/test/ActsValidateActsSpacePoints.sh
🟢	run_ci_tests: ../athena/AtlasTest/CITest/test/ActsValidateSeeds.sh
🟢	run_ci_tests: ../athena/AtlasTest/CITest/test/ActsValidateOrthogonalSeeds.sh
🟢	run_ci_tests: ../athena/AtlasTest/CITest/test/ActsValidateClusters.sh
🟢	run_ci_tests: ../athena/AtlasTest/CITest/test/ActsPersistifyEDM.sh
🟢	run_ci_tests: ../athena/AtlasTest/CITest/test/ActsKfRefitting.sh
🟢	run_ci_tests: python3 ../athena/Tracking/Acts/ActsGeometry/test/ActsExtrapolationAlgTest.py
🟢	run_ci_tests: python3 ../athena/Tracking/Acts/ActsGeometry/test/ActsITkTest.py
🟢	run_workflow_tests_run4_mc
🟢	run_workflow_tests_run2_mc
🔴	run_workflow_tests_run2_data
🟢	run_workflow_tests_run3_mc
🟢	run_workflow_tests_run3_data

[paulgessinger]

The actual output checks on the failed jobs seem to succeed:

INFO     ---------------------------------------------------------------------------------------
INFO     Running q442 Frozen Tier0 Policy Check on AOD for 60 events
INFO     Checking for reference override at https://actseos.web.cern.ch/ci/atlas/WorkflowReferences/main/q442/v24/myAOD.pool.root
INFO     No reference override found
INFO     Reading the reference file from location /cvmfs/atlas-nightlies.cern.ch/repo/data/data-art/WorkflowReferences/main/q442/v24/myAOD.pool.root
INFO     Neither '/builds/acts/acts-athena-ci/run/run_q442/q442_AOD_diff-exclusion-list.txt' nor '/builds/acts/acts-athena-ci/run/run_q442/q442_AOD_diff-interest-list.txt' files exist in the release.
INFO     No diff rules file exists, using the default list
INFO     Passed!

INFO     ---------------------------------------------------------------------------------------
INFO     Running q442 Frozen Tier0 Policy Check on ESD for 20 events
INFO     Checking for reference override at https://actseos.web.cern.ch/ci/atlas/WorkflowReferences/main/q442/v24/myESD.pool.root
INFO     No reference override found
INFO     Reading the reference file from location /cvmfs/atlas-nightlies.cern.ch/repo/data/data-art/WorkflowReferences/main/q442/v24/myESD.pool.root
INFO     Reading the diff rules file from location /builds/acts/acts-athena-ci/run/run_q442/q442_ESD_diff-exclusion-list.txt
INFO     Passed!

But then the q442 AOD metadata checks reports a mismatch. However, I don't see how this could be caused by these changes.

Also, this exact job failed with this exact difference also after #2460 went in, but then succeeded when #2516 was merged.

Could be an unrelated issue?

[paulgessinger]

When retrying, the job still fails (maybe something about the build is off?) but when I trigger a clean job it succeeds. I think we're good.