MSVertexTracketTool: Fix incorrect sign in tracklet chi squared calculation

The MSVertex Tracklet fitting had an incorrect sign in the chi squared calculation, causing all tracklet segments to fail reconstruction and no MS Vertices to be produced. This patch changes the sign to the correct value, returning the MSVertex performance to its run 2 behavior.

Fixes ATLASRECTS-7166

This merge request affects 1 package:

• MuonSpectrometer/MSVertexReconstruction/MSVertexTools

This merge request affects 1 file:

• MuonSpectrometer/MSVertexReconstruction/MSVertexTools/src/MSVertexTrackletTool.cxx

Adding @kluit ,@stavrop ,@pscholer ,@rosati ,@goetz ,@jojungge ,@apsallid as watchers

added MuonSpectrometer main review-pending-level-1 labels

I reconstructed ~150,000 llp events with the run 2 algorithm and with the run 3 algorithm with this sign change in place to confirm that the reconstruction behaves as expected, and presented the results in a muon software meeting a few weeks ago: https://indico.cern.ch/event/1409816/contributions/5927572/attachments/2844948/4973984/revering_muonSoftware_24_4_25.pdf

I also reconstructed the same set of run 3 samples with six different tasks to test the multithreading behavior of the MSVtx reconstruction, and confirmed that the outputs were identical from each task.

Original bug introduced in 0abd326b

added Run2-DataReco-output-changed Run2-MCReco-output-changed Run3-DataReco-output-changed Run3-MCReco-output-changed labels

CI Result FAILURE (hash 7b242452)

	Athena
externals
cmake
make
tests

Full details available on this CI monitor view. Check the JIRA CI status board for known problems
Athena: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-EL9 9966] (remote access info)

added RC Attention Required label

Changes in reference file are expected. Tagging @jcatmore, @jchapman, @nstyles, @christos, @jdandoy to assign the offline-sw-review-approved label

MR given back to developer due to CI tests failures. If it's expected, then I can approve it immediately because the code changes look good from L1 perspective.

removed review-pending-level-1 label

added review-user-action-required label

Yep, changes are expected

added review-pending-level-1 label

removed review-user-action-required label

removed review-pending-level-1 label

added review-approved label

Hello, may I ask if this is relevant for 24.0?

Potentially yes. I've no objections against putting it there as well

added 78 commits

• 7b242452...a495d73e - 76 commits from branch atlas:main
• 6e0b81d2 - MSVertexTracketTool: Fix incorrect sign in tracklet chi squared calculation
• 345ce6a2 - Update references

Compare with previous version

This merge request affects 2 packages:

• MuonSpectrometer/MSVertexReconstruction/MSVertexTools
• Tools/WorkflowTestRunner

Affected files list will not be printed in this case

Adding @kluit ,@goetz ,@pscholer ,@apsallid ,@rosati ,@jojungge ,@stavrop ,@pagessin as watchers

added Tools review-pending-level-1 labels and removed review-approved label

added offline-sw-review-approved label

resolved all threads

added 1 deleted label

removed 1 deleted label

CI Result FAILURE (hash 345ce6a2)

	Athena	AthSimulation	AthGeneration
externals
cmake
make
tests

Full details available on this CI monitor view. Check the JIRA CI status board for known problems
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-EL9 10063] (remote access info)

Jenkins please retry a build

This merge request affects 2 packages:

• MuonSpectrometer/MSVertexReconstruction/MSVertexTools
• Tools/WorkflowTestRunner

Affected files list will not be printed in this case

Adding @kluit ,@stavrop ,@jojungge ,@pagessin ,@goetz ,@pscholer ,@apsallid ,@rosati as watchers

enabled an automatic merge when the pipeline for 345ce6a2 succeeds

CI Result SUCCESS (hash 345ce6a2)

	Athena	AthSimulation	AthGeneration
externals
cmake
make
tests

Full details available on this CI monitor view. Check the JIRA CI status board for known problems
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-EL9 10069] (remote access info)

merged

mentioned in commit 74847b0e

added bugfix label