Draft: Improvements for Acts LRT pass: pt. 2
This MR follows up on !84542 (merged) and implements several additional fixes to recover the Legacy ITk LRT reconstruction efficiency:
- Refits SSS seeds to improve the initial seed parameter estimate, which in turn also switches the logic of the track finding to start from the bottom SP instead of the top SP
- Adds an option to allow the propagation to the first measurement surface in the initial track parameter estimate to fail, which was resulting in a large efficiency loss for displaced seeds
Along the way several bugs were identified in the seed refit logic that are also fixed here.
These changes bring the Acts efficiency above that of legacy Athena, while seemingly reducing the fake rate on the ttbar sample used in the CI considerably. Further study into the timing and performance on additional physics samples is still needed.
Edited by Jackson Carl Burzynski
