Flag for background particles (#7344)

Author: jgrosseo

Framework/Core/include/Framework/AnalysisDataModel.h

@@ -787,7 +787,7 @@ namespace mcparticle
 DECLARE_SOA_INDEX_COLUMN(McCollision, mcCollision);                                     //! MC collision of this particle
 DECLARE_SOA_COLUMN(PdgCode, pdgCode, int);                                              //! PDG code
 DECLARE_SOA_COLUMN(StatusCode, statusCode, int);                                        //! Status code directly from the generator
-DECLARE_SOA_COLUMN(Flags, flags, uint8_t);                                              //! ALICE specific flags. Do not use directly. Use the dynamic columns, e.g. producedByGenerator()
+DECLARE_SOA_COLUMN(Flags, flags, uint8_t);                                              //! ALICE specific flags, see MCParticleFlags. Do not use directly. Use the dynamic columns, e.g. producedByGenerator()
 DECLARE_SOA_SELF_INDEX_COLUMN_FULL(Mother0, mother0, int, "McParticles_Mother0");       //! Track index of the first mother
 DECLARE_SOA_SELF_INDEX_COLUMN_FULL(Mother1, mother1, int, "McParticles_Mother1");       //! Track index of the last mother
 DECLARE_SOA_SELF_INDEX_COLUMN_FULL(Daughter0, daughter0, int, "McParticles_Daughter0"); //! Track index of the first daugther
@@ -804,7 +804,9 @@ DECLARE_SOA_COLUMN(Vt, vt, float);
 DECLARE_SOA_DYNAMIC_COLUMN(Phi, phi,                                                    //! Phi
                            [](float px, float py) -> float { return static_cast<float>(M_PI) + std::atan2(-py, -px); });
 DECLARE_SOA_DYNAMIC_COLUMN(ProducedByGenerator, producedByGenerator, //! Particle produced by the generator or by the transport code
-                           [](uint8_t flags) -> bool { return (flags & 0x1) == 0x0; });
+                           [](uint8_t flags) -> bool { return (flags & o2::aod::mcparticle::enums::ProducedByTransport) == 0x0; });
+DECLARE_SOA_DYNAMIC_COLUMN(FromBackgroundEvent, fromBackgroundEvent, //! Particle from background event
+                           [](uint8_t flags) -> bool { return (flags & o2::aod::mcparticle::enums::FromBackgroundEvent) == o2::aod::mcparticle::enums::FromBackgroundEvent; });
 
 // DECLARE_SOA_EXPRESSION_COLUMN(Phi, phi, float, //! Phi: NOTE this waits that the atan2 function is defined for expression columns
 //                               static_cast<float>(M_PI) + natan2(-aod::mcparticle::py, -aod::mcparticle::px));
@@ -844,8 +846,7 @@ DECLARE_SOA_TABLE_FULL(StoredMcParticles, "McParticles", "AOD", "MCPARTICLE", //
                        mcparticle::Px, mcparticle::Py, mcparticle::Pz, mcparticle::E,
                        mcparticle::Vx, mcparticle::Vy, mcparticle::Vz, mcparticle::Vt,
                        mcparticle::Phi<mcparticle::Px, mcparticle::Py>,
-                       //  mcparticle::Eta<mcparticle::Px, mcparticle::Py, mcparticle::Pz>,
-                       mcparticle::ProducedByGenerator<mcparticle::Flags>);
+                       mcparticle::ProducedByGenerator<mcparticle::Flags>, mcparticle::FromBackgroundEvent<mcparticle::Flags>);
 
 DECLARE_SOA_EXTENDED_TABLE(McParticles, StoredMcParticles, "MCPARTICLE", //! Basic MC particle properties
                                                                          //  mcparticle::Phi,

Framework/Core/include/Framework/DataTypes.h

@@ -61,6 +61,14 @@ enum ForwardTrackTypeEnum : uint8_t {
 };
 } // namespace o2::aod::fwdtrack
 
+namespace o2::aod::mcparticle::enums
+{
+enum MCParticleFlags : uint8_t {
+  ProducedByTransport = 0x1,
+  FromBackgroundEvent = 0x2 // Particle from background event (may have been used several times)
+};
+} // namespace o2::aod::mcparticle::enums
+
 namespace o2::aod::run2
 {
 enum Run2EventSelectionCut {