Algorithm that selects the particles used in the FlavourTagging

Phys/FlavourTagging/CMakeLists.txt

@@ -22,6 +22,7 @@ gaudi_add_header_only_library(FlavourTaggingLib
 
 gaudi_add_module(FlavourTagging
     SOURCES
+	src/GetFlavourTaggingParticles.cpp
         src/BTagging.cpp
         src/BTaggingTool.cpp
         src/Classification/TaggingClassifierTMVA.cpp

Phys/FlavourTagging/src/GetFlavourTaggingParticles.cpp

+/*****************************************************************************\
+* (c) Copyright 2000-2021 CERN for the benefit of the LHCb Collaboration      *
+*                                                                             *
+* This software is distributed under the terms of the GNU General Public      *
+* Licence version 3 (GPL Version 3), copied verbatim in the file "COPYING".   *
+*                                                                             *
+* In applying this licence, CERN does not waive the privileges and immunities *
+* granted to it by virtue of its status as an Intergovernmental Organization  *
+* or submit itself to any jurisdiction.                                       *
+\*****************************************************************************/
+
+#include "GetFlavourTaggingParticles.h"
+
+// Declaration of the Algorithm Factory
+DECLARE_COMPONENT( GetFlavourTaggingParticles )
+
+LHCb::Particle::Selection GetFlavourTaggingParticles::operator()( const LHCb::Particles&       bCandidates,
+                                                                  const LHCb::Particle::Range& taggingParticles,
+                                                                  const LHCb::RecVertices&     primaryVertices,
+                                                                  const DetectorElement&       lhcbDetector ) const {
+  auto& geometry = *lhcbDetector.geometry();
+
+  LHCb::Particle::Selection selectedParticles;
+
+  for ( const auto& particle : taggingParticles ) {
+    const LHCb::VertexBase* bestParticlePV = m_relatedPVTool->relatedPV( particle, primaryVertices );
+
+    for ( const auto& bCand : bCandidates ) {
+      const LHCb::VertexBase* bestbCandPV = m_relatedPVTool->relatedPV( bCand, primaryVertices );
+      if ( bestbCandPV == bestParticlePV ) {
+        selectedParticles.insert( particle );
+        break;
+      }
+
+      auto minIpChi2 = calcMinIpChi2( *particle, primaryVertices, geometry );
+      if ( minIpChi2.has_value() ) {
+        if ( minIpChi2.value() > m_minIpChi2 ) {
+          selectedParticles.insert( particle );
+          break;
+        }
+      }
+    }
+  }
+
+  m_inCount += taggingParticles.size();
+  m_outCount += selectedParticles.size();
+  return selectedParticles;
+}
+
+std::optional<double> GetFlavourTaggingParticles::calcMinIpChi2( const LHCb::Particle&    part,
+                                                                 const LHCb::RecVertices& vertices,
+                                                                 const IGeometryInfo&     geometry ) const {
+  double minIpChi2 = std::numeric_limits<double>::max();
+
+  for ( auto const* vertex : vertices ) {
+    auto tempIpChi2 = calcIpChi2( part, *vertex, geometry );
+    if ( tempIpChi2.has_value() ) {
+      if ( tempIpChi2.value() < minIpChi2 ) { minIpChi2 = tempIpChi2.value(); }
+    }
+  }
+  if ( minIpChi2 < std::numeric_limits<double>::max() ) return minIpChi2;
+  return std::nullopt;
+}
+
+std::optional<double> GetFlavourTaggingParticles::calcIpChi2( const LHCb::Particle&   part,
+                                                              const LHCb::VertexBase& vertex,
+                                                              const IGeometryInfo&    geometry ) const {
+  double     ip     = -100.0;
+  double     ipChi2 = 0;
+  StatusCode sc     = m_distCalcTool->distance( &part, &vertex, ip, ipChi2, geometry );
+  if ( sc ) return ipChi2;
+  return std::nullopt;
+}
\ No newline at end of file

Phys/FlavourTagging/src/GetFlavourTaggingParticles.h

+/*****************************************************************************\
+* (c) Copyright 2000-2021 CERN for the benefit of the LHCb Collaboration      *
+*                                                                             *
+* This software is distributed under the terms of the GNU General Public      *
+* Licence version 3 (GPL Version 3), copied verbatim in the file "COPYING".   *
+*                                                                             *
+* In applying this licence, CERN does not waive the privileges and immunities *
+* granted to it by virtue of its status as an Intergovernmental Organization  *
+* or submit itself to any jurisdiction.                                       *
+\*****************************************************************************/
+#pragma once
+
+// from Gaudi
+#include "GaudiAlg/Transformer.h"
+
+// from LHCb
+#include "DetDesc/DetectorElement.h"
+#include "DetDesc/GenericConditionAccessorHolder.h"
+#include "Event/Particle.h"
+#include "Event/RecVertex.h"
+#include "Kernel/IDistanceCalculator.h"
+#include "Kernel/IRelatedPVFinder.h"
+
+class GetFlavourTaggingParticles
+    : public Gaudi::Functional::Transformer<LHCb::Particle::Selection(
+                                                const LHCb::Particles&, const LHCb::Particle::Range&,
+                                                const LHCb::RecVertices&, const DetectorElement& ),
+                                            LHCb::DetDesc::usesConditions<DetectorElement>> {
+public:
+  /// Standard constructor
+  GetFlavourTaggingParticles( const std::string& name, ISvcLocator* pSvcLocator )
+      : Transformer( name, pSvcLocator,
+                     {KeyValue{"BCandidates", ""}, KeyValue{"TaggingParticles", ""}, KeyValue{"PrimaryVertices", ""},
+                      KeyValue{"StandardGeometry", "/dd/Structure/LHCb"}},
+                     KeyValue{"FlavourTaggingParticles", ""} ) {}
+
+  LHCb::Particle::Selection operator()( const LHCb::Particles&       bCandidates,
+                                        const LHCb::Particle::Range& taggingParticles,
+                                        const LHCb::RecVertices&     primaryVertices,
+                                        const DetectorElement& ) const override;
+
+private:
+  Gaudi::Property<double> m_minIpChi2{this, "MinIpChi2", 6.,
+                                      "Tagging particle requirement: Minimum IPChi2 wrt to all PVs"};
+
+  std::optional<double> calcMinIpChi2( const LHCb::Particle& part, const LHCb::RecVertices& vertices,
+                                       const IGeometryInfo& geometry ) const;
+
+  std::optional<double> calcIpChi2( const LHCb::Particle& part, const LHCb::VertexBase& vertex,
+                                    const IGeometryInfo& geometry ) const;
+
+  ToolHandle<IRelatedPVFinder> m_relatedPVTool{
+      this, "RelatedPVFinderTool", "GenericParticle2PVRelator__p2PVWithIPChi2_OnlineDistanceCalculatorName_"};
+  ToolHandle<IDistanceCalculator> m_distCalcTool{this, "DistanceCalculatorTool", "LoKi::TrgDistanceCalculator"};
+
+  mutable Gaudi::Accumulators::SummingCounter<> m_inCount{this, "#InputParticles"};
+  mutable Gaudi::Accumulators::SummingCounter<> m_outCount{this, "#OutputParticles"};
+};