[PWGHF] add correlated bkg to Lc tree creator. (#11807)

Co-authored-by: Mattia Faggin <mfaggin@cern.ch>

Author: mfaggin

PWGHF/TableProducer/treeCreatorLcToPKPi.cxx

@@ -17,20 +17,20 @@
 /// \author Nicolo' Jacazio <nicolo.jacazio@cern.ch>, CERN
 /// \author Luigi Dello Stritto <luigi.dello.stritto@cern.ch>, CERN
 
-#include <algorithm>
-#include <utility>
-#include <vector>
+#include "PWGHF/Core/HfHelper.h"
+#include "PWGHF/DataModel/CandidateReconstructionTables.h"
+#include "PWGHF/DataModel/CandidateSelectionTables.h"
+
+#include "Common/DataModel/Centrality.h"
+#include "Common/DataModel/Multiplicity.h"
 
 #include "CommonConstants/PhysicsConstants.h"
 #include "Framework/AnalysisTask.h"
 #include "Framework/runDataProcessing.h"
 
-#include "Common/DataModel/Centrality.h"
-#include "Common/DataModel/Multiplicity.h"
-
-#include "PWGHF/Core/HfHelper.h"
-#include "PWGHF/DataModel/CandidateReconstructionTables.h"
-#include "PWGHF/DataModel/CandidateSelectionTables.h"
+#include <algorithm>
+#include <utility>
+#include <vector>
 
 using namespace o2;
 using namespace o2::framework;
@@ -388,6 +388,7 @@ struct HfTreeCreatorLcToPKPi {
   Configurable<bool> applyMl{"applyMl", false, "Whether ML was used in candidateSelectorLc"};
   Configurable<bool> keepOnlySignalMc{"keepOnlySignalMc", false, "Fill MC tree only with signal candidates"};
   Configurable<bool> keepOnlyBkg{"keepOnlyBkg", false, "Fill MC tree only with background candidates"};
+  Configurable<bool> keepCorrBkgMC{"keepCorrBkgMC", false, "Flag to keep correlated background sources (Λc+ -> p K− π+ π0, p π− π+, p K− K+ and other charm hadrons)"};
   Configurable<double> downSampleBkgFactor{"downSampleBkgFactor", 1., "Fraction of candidates to store in the tree"};
   Configurable<float> downSampleBkgPtMax{"downSampleBkgPtMax", 100.f, "Max. pt for background downsampling"};
 
@@ -927,9 +928,11 @@ struct HfTreeCreatorLcToPKPi {
         const int sigbgstatus = determineSignalBgStatus(candidate, candFlag);
         const bool isMcCandidateSignal = (sigbgstatus == Prompt) || (sigbgstatus == NonPrompt);
         const bool passSelection = functionSelection >= selectionFlagLc;
-        const bool keepAll = !keepOnlySignalMc && !keepOnlyBkg;
+        const bool keepAll = !keepOnlySignalMc && !keepOnlyBkg && !keepCorrBkgMC;
+        const int flag = candidate.flagMcMatchRec();
+        const bool isCorrBkg = (std::abs(flag) != 0 && std::abs(flag) != o2::hf_decay::hf_cand_3prong::DecayChannelMain::LcToPKPi);
         const bool notSkippedBkg = isMcCandidateSignal || candidate.pt() > downSampleBkgPtMax || pseudoRndm < downSampleBkgFactor;
-        if (passSelection && notSkippedBkg && (keepAll || (keepOnlySignalMc && isMcCandidateSignal) || (keepOnlyBkg && !isMcCandidateSignal))) {
+        if (passSelection && notSkippedBkg && (keepAll || (keepOnlySignalMc && isMcCandidateSignal) || (keepOnlyBkg && !isMcCandidateSignal) || (keepCorrBkgMC && isCorrBkg))) {
           if (fillCandidateLiteTable) {
             fillLiteTable<IsMc, reconstructionType>(candidate, candidateMlScore, candFlag);
           } else {