Provide track states expected by LHCb (Gaudi) event model
Related
Prompted by discussions in !1113 (merged) and !1124 (merged). (Not resolved by either).
Description
Quoting from the description of !1124 (merged):
A fixed set of track states for each
LHCb::Event::v3::TrackTypeis part of the definition ofLHCb::Event::v3::Tracks. This differs from the previous iterations of the Track definition that had variable sets of states. The track state information available to the GaudiAllen..ToV2Tracks converters is, in general, inconsistent with the that associated with the corresponding LHCb::Event::v3::TrackType. The following table indicates what is provided by the previous collection of converters and what is expected for the targetedLHCb::Event::v3::TrackType.
| v2 converter | States provided | LHCb::Event::v3::TrackType | States of v3::TrackType |
|---|---|---|---|
| GaudiAllenVeloToV2Tracks |
ClosestToBeam1
|
Velo, VeloBackward |
ClosestToBeam, FirstMeasurement, LastMeasurement
|
| GaudiAllenUTToV2Tracks |
ClosestToBeam1, EndVelo1
|
Upstream |
ClosestToBeam, FirstMeasurement, LastMeasurement, BegRich1, EndRich1
|
| GaudiAllenForwardToV2Tracks |
ClosestToBeam2
|
FittedForward | ClosestToBeam |
The converters implemented in !1124 (merged) includes a compromise between what was immediately available from Allen and what was expected for LHCb::Event::v3::Tracks. The compromise was a linear extrapolation to the z position of each expected state for the given LHCb::Event::v3::Tracks type from the nearest Allen state. The conclusion of the review discussion on the matter was that Allen should provide proper estimates for the expected states to a future iteration of the Allen-to-LHCb track converters.