Merge branch '24.0_fix_z0err_of_TRT_Standalone_tracks' into '24.0'

Optionally use current perigee when recomputing perigee for TRT standalone tracks.

See merge request !75652

Reconstruction/RecoTools/TrackToVertex/src/TrackToVertex.cxx

 /*
-  Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
 */
 
 ///////////////////////////////////////////////////////////////////
@@ -14,7 +14,6 @@
 #include "TrkSurfaces/StraightLineSurface.h"
 #include "TrkDetDescrUtils/GeometryStatics.h"
 #include "TrkParameters/TrackParameters.h"
-#include "TrkTrack/Track.h"
 #include "VxVertex/VxCandidate.h"
 #include "VxVertex/RecVertex.h"
 
@@ -137,7 +136,9 @@ std::unique_ptr<Trk::Perigee> Reco::TrackToVertex::perigeeAtVertex(const EventCo
   Trk::PerigeeSurface persf(gp);
   std::unique_ptr<Trk::Perigee> vertexPerigee;
   std::unique_ptr<Trk::TrackParameters> extrapResult =
-    m_extrapolator->extrapolateTrack(ctx,track, persf);
+     !startAtOriginalPerigee(track)
+     ? m_extrapolator->extrapolateTrack(ctx,track, persf)
+     : m_extrapolator->extrapolate(ctx, *(track.perigeeParameters()), persf);
   if (extrapResult && extrapResult->surfaceType() == Trk::SurfaceType::Perigee) {
     vertexPerigee.reset( static_cast<Trk::Perigee*>(extrapResult.release()));
   }
@@ -181,7 +182,9 @@ Reco::TrackToVertex::perigeeAtBeamline(
 
   std::unique_ptr<Trk::Perigee> vertexPerigee;
   std::unique_ptr<Trk::TrackParameters> extrapResult =
-    m_extrapolator->extrapolateTrack(ctx,track, persf);
+     !startAtOriginalPerigee(track)
+     ? m_extrapolator->extrapolateTrack(ctx,track, persf)
+     : m_extrapolator->extrapolate(ctx,*(track.perigeeParameters()), persf);
   if (extrapResult && extrapResult->surfaceType() == Trk::SurfaceType::Perigee) {
     vertexPerigee.reset(static_cast<Trk::Perigee*>(extrapResult.release()));
   }
@@ -263,7 +266,9 @@ std::unique_ptr<Trk::TrackParameters> Reco::TrackToVertex::trackAtBeamline(const
 std::unique_ptr<Trk::TrackParameters> Reco::TrackToVertex::trackAtBeamline(const EventContext& ctx, const Trk::Track& trk,
                                 const Trk::StraightLineSurface* beamline) const
 {
-  return m_extrapolator->extrapolateTrack(ctx, trk, *beamline);
+  return !startAtOriginalPerigee(trk)
+     ? m_extrapolator->extrapolateTrack(ctx, trk, *beamline)
+     : m_extrapolator->extrapolate(ctx,*(trk.perigeeParameters()), *beamline);
 }
 
 std::unique_ptr<Trk::TrackParameters> Reco::TrackToVertex::trackAtBeamline(const EventContext& ctx, const Trk::TrackParameters& tpars,

Reconstruction/RecoTools/TrackToVertex/src/TrackToVertex.h

 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
 */
 
 ///////////////////////////////////////////////////////////////////
@@ -16,6 +16,7 @@
 // Trk
 #include "ITrackToVertex/ITrackToVertex.h"
 #include "TrkParameters/TrackParameters.h"
+#include "TrkTrack/Track.h"
 #include "GeoPrimitives/GeoPrimitives.h"
 #include "BeamSpotConditionsData/BeamSpotData.h"
 #include "TrkExInterfaces/IExtrapolator.h"
@@ -25,7 +26,6 @@ namespace Rec {
 }
 
 namespace Trk {
-  class Track;
   class StraightLineSurface;
 }
 
@@ -127,8 +127,17 @@ namespace Reco {
         const Trk::StraightLineSurface* beamline) const override final;
 
     private:
+      inline bool startAtOriginalPerigee(const Trk::Track &track) const {
+        return m_startTRTSAAtPerigee.value()
+            && track.info().patternRecognition().test(Trk::TrackInfo::TRTStandalone)
+            && track.perigeeParameters();
+      }
+
       ToolHandle<Trk::IExtrapolator>
         m_extrapolator {this, "Extrapolator", "Trk::Extrapolator/AtlasExtrapolator"}; //!< ToolHandle for Extrapolator
+      Gaudi::Property<bool> m_startTRTSAAtPerigee
+        {this, "StartTRTStandaloneTracksAtOriginalPerigee", false,
+         "When extrapolating TRT standalone start at their original perigee which may have a more realistic covariance"};
 
       const static Amg::Vector3D s_origin; //!< static origin
   };