new measurement selector outlier cut
Add outlier χ² < 25 cut and remove maxOutliers
cut.
- This change only became viable with ACTS v36.1.0, which included #3474.
- Since this outlier cut is the same as the hole cut (χ² < 25), this means the CKF no longer finds outliers, which could previously be any other hit on the surface.
- The legacy Athena cuts are tighter: χ² < 9, 25 (hole, outlier). In ACTS, these would lead to a 2.3% reduction in 1 GeV single muon efficiency.
- This change still has a 0.2% reduction in 1 GeV single muon efficiency; less of an effect in other samples.
- The small change will require a CI counts reference update.
- For ttbar+PU200, this MR gives a ~5% speedup in the
TrackFindingAlg
.