[PWGLF] Update MC background flagging in decay3bodybuilder

PWGLF/TableProducer/Nuspex/decay3bodybuilder.cxx

@@ -1,4 +1,4 @@
 // Copyright 2019-2020 CERN and copyright holders of ALICE O2.
 // See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
 // All rights not expressly granted are reserved.
 //
@@ -142,7 +142,7 @@
   // CCDB options
   struct : ConfigurableGroup {
     std::string prefix = "ccdb";
     Configurable<std::string> ccdburl{"ccdb-url", "http://alice-ccdb.cern.ch", "url of the ccdb repository"};
     Configurable<std::string> grpPath{"grpPath", "GLO/GRP/GRP", "Path of the grp file"};
     Configurable<std::string> grpmagPath{"grpmagPath", "GLO/Config/GRPMagField", "CCDB path of the GRPMagField object"};
     Configurable<std::string> lutPath{"lutPath", "GLO/Param/MatLUT", "Path of the Lut parametrization"};
@@ -197,8 +197,8 @@
     std::string prefix = "mixingOpts";
     Configurable<int> n3bodyMixing{"n3bodyMixing", 0, "Number of decay3bodys to mix: 0 - value set to maximum bin entry in hDecay3BodyRadiusPhi, > 0 - manual setting"};
     Configurable<int> mixingType{"mixingType", 0, "0: mix V0 from one event with bachelor from another, 1: mix pion and bachelor from one event with proton from another, 1: mix proton and bachelor from one event with pion from another "};
     ConfigurableAxis bins3BodyRadius{"mixingOpts.bins3BodyRadius", {VARIABLE_WIDTH, 0.0f, 2.0f, 4.0f, 7.0f, 10.0f, 14.0f, 18.0f, 22.0f, 30.0f, 40.0f}, "Mixing bins - 3body radius"};
     ConfigurableAxis bins3BodyPhi{"mixingOpts.bins3BodyPhi", {VARIABLE_WIDTH, -180 * o2::constants::math::Deg2Rad, -120 * o2::constants::math::Deg2Rad, -60 * o2::constants::math::Deg2Rad, 0, 60 * o2::constants::math::Deg2Rad, 120 * o2::constants::math::Deg2Rad, 180 * o2::constants::math::Deg2Rad}, "Mixing bins - 3body phi (rad)"};
     ConfigurableAxis bins3BodyPhiDegree{"mixingOpts.bins3BodyPhiDegree", {VARIABLE_WIDTH, -180, -120, -60, 0, 60, 120, 180}, "Mixing bins - 3body phi (degree)"};
     ConfigurableAxis bins3BodyPosZ{"mixingOpts.bins3BodyPosZ", {VARIABLE_WIDTH, -500.0f, -200.0f, -100.0f, -70.0f, -60.0f, -50.0f, -40.0f, -35.0f, -30.0f, -25.0f, -20.0f, -15.0f, -13.0f, -10.0f, -8.0f, -6.0f, -4.0f, -2.0f, 0.0f, 2.0f, 4.0f, 6.0f, 8.0f, 10.0f, 13.0f, 15.0f, 20.0f, 25.0f, 30.0f, 35.0f, 40.0f, 50.0f, 60.0f, 70.0f, 100.0f, 200.0f, 500.0f}, "3body SV z position"};
     Configurable<bool> selectPVPosZ3bodyMixing{"selectPVPosZ3bodyMixing", true, "Select same pvPosZ events in case of 3body mixing"};
@@ -307,7 +307,7 @@
       }
       matCorr = o2::base::Propagator::MatCorrType::USEMatCorrTGeo;
     }
     if (useMatCorrType == 2) {
       LOGF(info, "LUT correction requested, loading LUT");
       lut = o2::base::MatLayerCylSet::rectifyPtrFromFile(ccdb->get<o2::base::MatLayerCylSet>(ccdbConfigurations.lutPath));
       matCorr = o2::base::Propagator::MatCorrType::USEMatCorrLUT;
@@ -534,7 +534,7 @@
     KFParticle::SetField(d_bz);
 #endif
 
     if (useMatCorrType == 2) {
       // setMatLUT only after magfield has been initalized
       // (setMatLUT has implicit and problematic init field call if not)
       LOG(info) << "Loading material look-up table for timestamp: " << timestamp;
@@ -594,7 +594,7 @@
     helper.fitterV0.setBz(magField);
     helper.fitter3body.setBz(magField);
 
     if (useMatCorrType == 2) {
       // setMatLUT only after magfield has been initalized (setMatLUT has implicit and problematic init field call if not)
       o2::base::Propagator::Instance()->setMatLUT(lut);
     }
@@ -651,7 +651,7 @@
         }
 
         // event selection
         if (!collision.selection_bit(aod::evsel::kIsTriggerTVX) || !collision.selection_bit(aod::evsel::kNoTimeFrameBorder) || (collision.posZ() >= 10.0f || collision.posZ() <= -10.0f)) {
           continue;
         }
 
@@ -704,7 +704,7 @@
         if (!collision.selection_bit(aod::evsel::kNoITSROFrameBorder) && !disableITSROFCut) { // ITS ROF boarder cut if not disabled
           continue;
         }
         if (!collision.selection_bit(aod::evsel::kIsTriggerTVX) || !collision.selection_bit(aod::evsel::kNoTimeFrameBorder) || (collision.posZ() >= 10.0f || collision.posZ() <= -10.0f)) {
           continue;
         }
         // Zorro
@@ -806,7 +806,7 @@
           if (!doStoreMcBkg) {
             continue; // if not storing MC background, skip candidates where at least one daughter is not matched to MC particle
           } else {
-            this3BodyMCInfo.motherLabel = -5; // at least one non-matched daughter
+            this3BodyMCInfo.motherLabel = -5; // at least one of the daughters not matched to MC particle
             // fill analysis table (only McVtx3BodyDatas is filled here)
             fillAnalysisTables();
           }
@@ -1053,7 +1053,7 @@
         doMixing(collision1, trackProton0, trackPion1, trackDeuteron1, magFieldCol1);
       }
       // mix pion
       if (mixingOpts.mixingType == 2) {
         doMixing(collision0, trackProton0, trackPion1, trackDeuteron0, magFieldCol0);
         doMixing(collision1, trackProton1, trackPion0, trackDeuteron1, magFieldCol1);
       }
@@ -1200,10 +1200,11 @@
     // global mother ID: proton, pion, and deuteron have common mother and it's a hypertriton
 
     // first, check identity of MC daughters
-    if (std::abs(mcParticlePr.pdgCode()) != PDG_t::kProton || std::abs(mcParticleDe.pdgCode()) != o2::constants::physics::Pdg::kDeuteron || (std::abs(mcParticlePi.pdgCode()) != PDG_t::kPiPlus && std::abs(mcParticlePi.pdgCode()) != PDG_t::kMuonMinus)) {
-      return -4;
+    if (std::abs(mcParticlePr.pdgCode()) != PDG_t::kProton || (std::abs(mcParticlePi.pdgCode()) != PDG_t::kPiPlus && std::abs(mcParticlePi.pdgCode()) != PDG_t::kMuonMinus)) {
+      return -4; // at least one of the daughters has wrong identity (in this case it's either proton or pion wrong identity)
     }
-    // check if the pion track is a muon coming from a pi -> mu + vu decay, if yes, take the mother pi
+    // --> now the proton is a proton and the pion is either a pi+ or a muon
+    // check if the pion track is a muon coming from a pi -> mu + vu decay, if yes, take the mother pi, if not, fill as background
     auto mcParticlePiTmp = mcParticlePi;
     if (std::abs(mcParticlePiTmp.pdgCode()) == PDG_t::kMuonMinus) {
       bool isMuonReco = false;
@@ -1216,9 +1217,10 @@
       }
       // If the track is a muon but none of its mothers is a pi+, treat as wrong identity
       if (!isMuonReco) {
-        return -4;
+        return -4; // at least one of the daughters has wrong identity (in this case it's pion wrong identity)
       }
     }
+    // --> now proton and pion have correct identity
 
     // now first check if the proton and pion have the same mother and it is a Lambda
     for (const auto& motherPr : mcParticlePr.template mothers_as<aod::McParticles>()) {
@@ -1228,6 +1230,13 @@
         }
       }
     }
+    // --> now proton and pion have correct identity and are not from a common mother Lambda
+
+    // now check if deuteron has correct identity
+    if (std::abs(mcParticleDe.pdgCode()) != o2::constants::physics::Pdg::kDeuteron) {
+      return -4; // at least one daughter has wrong identity (in this case it's the deuteron)
+    }
+    // --> now the deuteron has correct identity
 
     // now check if all three daughters have the same mother
     int momID = -1;