Fix of the Muon Spectrometer slow particle (MuGirlStau) reconstruction chain (temporary/flag-enabled)
This MR is a bug fix that accomplishes two tasks to bring the performance of the Muon Spectrometer slow particle reconstruction algorithm (MuGirlStau) to back to R21 levels. The performance degraded between R21 and R22 and then again between R22 and R25. The second drop in efficiency (between R22 and R25) is fixed by patching a semantic bug, which was already done on main (see !74641 (merged)). The first drop in efficiency is fixed by ensuring that the value of particle speed (beta) passed to MuonPRDSelectionTool is non-default (i.e. not 1). The tool that accomplished this in R21 (StauBetaToFTool) was not ported from R21 to R22. Changes in the reconstruction efficiency for a 700 GeV, 3000 ns slepton sample are illustrated below. The efficiency is fully restored in R24/R25 relative to R21:
Changes that restore the efficiency drop between R25/R24 and R22 are identical to those in the MR linked above. Changes that restore the efficiency drop between R22 and R21 are new and will be enabled by a flag. As such, all frozen-tier0-violating changes in this MR have already been merged into main, and constitute a bug fix as opposed to a feature change. Changes in CPU time as a result of this bug fix/phase I of the patch are shown below and were deemed to be acceptable. Phase II incurs no increase in CPU time, and is hidden by a flag as to not affect the default reco output.
Changes in CPU time (after Phase I of patch, more details in !71011 (merged))
| Algorithm | main [ms] | patched [ms] |
|---|---|---|
| MuonInDetToMuonSystemExtensionAlg | 46880 | 53448 |
| MuonInDetToMuonSystemExtensionAlg_LRT | 56940 | 65065 |
| MuonInsideOutRecoAlg | 88395 | 92216 |
| MuonCombinedAlg | 93904 | 97335 |
| MuonCombinedAlg_LRT | 29706 | 30284 |
| MuGirlStauAlg | 3184 | 12690 |
| MuGirlAlg_LRT | 73245 | 76415 |
A sweep into main should be ignored since these changes will be implemented there permanently (i.e. without a flag to enable them).
Tagging @caiy, @spagan, @gdyckes, @jojungge, @ivivarel, @kluit
Resources
Relevant merge requests:
- Main MR to restore performance of MuGirlStau to R22 levels in main: !74641 (merged)
- Related fixes/optimizations needed for port to work: !72196 (merged)
Presentations: